custom Made Exhaust System

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Nez

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Ok guys need help again :) I just been to Top Gear Custom made Exhaust System in heys and after they looked at the car they said they can make a custom made Exhaust System for my car plus sport cat all for £450 incl fitting :)

One thing I want to ask you guys they said that they will fit one Sport cat other then two cats and they said that it won't make any difference to the performace?

So what you guys think? and have anyone tried this with their S4 before?
 
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Doesn't make sense...Do mean there'll be 3 cats on the system? Or they were originaly just going to put one sport cat on and leave the other standard (I'm assuming that each side has it's own cat to begin with), (eek!) purt two sports cats on or.... have both pipes going through 1 sports cat.

Not got an S4, or a sport system but always curious!
 
dieselfitter251 said:
Doesn't make sense...Do mean there'll be 3 cats on the system? Or they were originaly just going to put one sport cat on and leave the other standard (I'm assuming that each side has it's own cat to begin with), (eek!) purt two sports cats on or.... have both pipes going through 1 sports cat.

Not got an S4, or a sport system but always curious!
Click to expand...

The S4 standard as 2 cats but the guys at custom Exh will make it to one cat and one signal pipe other then standard 2 pipes :) so there will be only one sport cat and one straight pipe all the way to the back box.
 
audi upgrades
what kind of thing are you after , performance, sound etc if they havent done s4s before i would give them the recommended pipe sizes etc . Its a good idea to see what the big boys are doing and try to duplicate the designs etc. Ive had loads of systems and my current is the ss autochrome /xs power system with piggies . It was quiet compared to my last straight through system and as told by many others when i get it back on the road i will be removing the back box to get the best sound without in cabin drone
 
Are they doing the downpipes as well? Standard S4/RS4 downpipes have a pre-cat and a cat in each, so 4 cats effectively.
 
thats it the precats at the manifold make a big difference but for that money i very much doubt they will be .
 
I dont think running one cat is a good idea.

Cats are a restriction, two cats are less of a restriction than one cat.

S4 has 4 cats as standard. Two in the downpipe elbows immediately after the turbo, and two under the car.

Ditch the ones in the downpipes by either doing the so-called "piggy pipe mod" then replace the ones underneath with a pair of sport cats.

The standard system also has two pipes into the Y section then a single pipe from there, the better aftermarket systems tend to run two pipes all the way out to the backbox.
 
Its going to be something like this:


AUDI_tt_hiflow_cat.jpg


But my one will be two pipes coming from the downpipe to the signal cat and all the way to the back box and they will use 2.5" pipe :blink:
 
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aragorn said:
I dont think running one cat is a good idea.

Cats are a restriction, two cats are less of a restriction than one cat.

S4 has 4 cats as standard. Two in the downpipe elbows immediately after the turbo, and two under the car.

Ditch the ones in the downpipes by either doing the so-called "piggy pipe mod" then replace the ones underneath with a pair of sport cats.

The standard system also has two pipes into the Y section then a single pipe from there, the better aftermarket systems tend to run two pipes all the way out to the backbox.
Click to expand...

They will only remove the the cats under the car not the two which is ditch on the downpipes.
 
aragorn said:
Nah thats going to be proper ****.

Even the stock exhaust is larger than 2.5" iirc?
Click to expand...

I am not sure 100% if they use the 2.5" pipe but I will ask before they start work on the car tomorrow but I know for sure that they will use a big sport cat so that have to be bigger then 2.5" :)

Here I find a picture almost some as the setup that the will do:

URL]
 
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I've got a Milltek single which is a single 3" pipe. The Milltek dual is two 2.5" pipes. A single 2.5" pipe sounds very restrictive.

Look at the cross sectional area of those three for comparison:
3" single = 7.1sq"
2.5" twin = 9.8sq"
2.5" single = 4.9sq"

So are they replacing the downpipes then or just cutting the main cats off the existing ones? People tend to remove their pre-cats (at the top of each downpipe) to help turbo spool up and reduce EGT's at high boost, but you seem to be suggesting that this place will be leaving the Pre-Cats and removing the main cats... then replacing the main cats with sports cats.

ps. Have you forgotten that you're selling this car? lol
 
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Blue_Thunder said:
I've got a Milltek single which is a single 3" pipe. The Milltek dual is two 2.5" pipes. A single 2.5" pipe sounds very restrictive.

Look at the cross sectional area of those three for comparison:
3" single = 7.1sq"
2.5" twin = 9.8sq"
2.5" single = 4.9sq"

So are they replacing the downpipes then or just cutting the main cats off the existing ones? People tend to remove their pre-cats (at the top of each downpipe) to help turbo spool up and reduce EGT's at high boost, but you seem to be suggesting that this place will be leaving the Pre-Cats and removing the main cats... then replacing the main cats with sports cats.

ps. Have you forgotten that you're selling this car? lol
Click to expand...

They will just cut the main cats and replace it with one signal sport cat :) I can tell them to remove the pre-cats but will the car be fine with one singal sport cat :blink: and I think they will use 3" not 2.5" sorry my mistake.

"ps. Have you forgotten that you're selling this car? lol"

Yea I was but now money is ok so I am keeping it ;)
 
You're not really listening to what we're saying

A Cat is THE most restrictive part of the exhaust. You've currently got two precats and two main cats and are going to replace it with two precats feeding into one "sport" cat. Cant you see that even if the sport cat flows better than normal, its still not going to flow as well as two cats with twice the surface area?

Its one of those things, either do the job properly, with piggie pipes and TWO sport cats, or leave it well alone.
 
I know people who are running no cats at all on their S4's. If you have a friendly MOT station, it wouldn't be a problem.

I've had no pre-cats for over a year now and RS4 main cats (200 cell), i've not failed emissions for an MOT.

Depends what your exhaust place classes as a Sports cat. 200 cell should be fine without pre-cats, but I think you'd struggle if their sports cat is 100 cell. If their sports cat is more than 200 cell, you would be better off going elsewhere.

Have you looked into the XS-Power system from eBay? Very good for the money, sounds excellent and have been shown to give performance gains (I've seen +10bhp on a totally stock car).
 

Mo power, mo problems ......

Sounds like this ^^^^ in a nut shell! Also sounds to me as though you have to be really carefull when doing custom mods.. Standard mods themselves are 99% of the time tried and tested. If you're going to do something that is a little bit off base you'd better have your sums right...

Not any help for the post but just an observation.

Nez. Are they giving you any guarantees about power gains. Maybe use the guarantee to help with any 'fixes' that may be required.
 
aragorn said:
You're not really listening to what we're saying

A Cat is THE most restrictive part of the exhaust. You've currently got two precats and two main cats and are going to replace it with two precats feeding into one "sport" cat. Cant you see that even if the sport cat flows better than normal, its still not going to flow as well as two cats with twice the surface area?

Its one of those things, either do the job properly, with piggie pipes and TWO sport cats, or leave it well alone.
Click to expand...

I understand what you mean and I know the most restrictive parts of exhaust is the cats but S4 engine are very diggy so I don't want any dash lights to light up after the exh system thats why I am asking all these question :) sorry if it the questions sounds stupid.

And I undrstand what you mean by taking all the cats and fitting one cat will make no difference but they guys at the Custom exh said that they will make the exhuast the way that it make difference so tomorrow I will speak to them before the start the job.
 
dieselfitter251 said:

Mo power, mo problems ......

Sounds like this ^^^^ in a nut shell! Also sounds to me as though you have to be really carefull when doing custom mods.. Standard mods themselves are 99% of the time tried and tested. If you're going to do something that is a little bit off base you'd better have your sums right...

Not any help for the post but just an observation.

Nez. Are they giving you any guarantees about power gains. Maybe use the guarantee to help with any 'fixes' that may be required.
Click to expand...

Oh yea sure they will give guarantees for the power and life time guarantee for the Exhuast system.

Thats why when I asked them about the singal cat and pipe they said that they will use a bigger sport cat and it will not affect the flow of the exhaust or restricted the flow of the exhaust.
 
Cool. Interested in the outcome. I don't modify and can't afford to but hopefully that ain't a permanent situation :sly:... Always interested..
 
like i say ive had 2 custom systems both of which have had changes so many times and start to look ****. This new xs-power cheapy one is by far the best performing system and also the nicest looking system in build quality terms . I run no pre cats (piggies) and no main cats . It has a medium centre box and medium rear box . Its very quiet as compared to systems before but you can always do a rear or centre box delete.
vids below with rear delete

http://www.audizine.com/forum/showthread.php?t=260365
 
andybnwc said:
like i say ive had 2 custom systems both of which have had changes so many times and start to look ****. This new xs-power cheapy one is by far the best performing system and also the nicest looking system in build quality terms . I run no pre cats (piggies) and no main cats . It has a medium centre box and medium rear box . Its very quiet as compared to systems before but you can always do a rear or centre box delete.
vids below with rear delete

http://www.audizine.com/forum/showthread.php?t=260365
Click to expand...

I have looked at this exhaust system but most commen problem they have is the fitting sometimes it need a little modification to fit it and thats why I didn't went for it and also people who fitted into S4 said sometimes it lakes too.
 
Well to clarify my position...

If i took an S4 (or any V engine) into an exhaust place, and they tried to tell me that running a single cat would be "better" than two, i would turn around and walk out the door.

Its your money, you spend it however you wish, just take on board the fact that regardless of what crap they try to spin, one cat will be more restrictive than two, and IMO its pointless doing ANYTHING to the exhaust without first removing the pre-cats.
 
is the piggie pipe the same for the 1.8tqs? as im think of havin mine done just wonder sorry to highjack this thread!!!:asskicking:
 
Depends how you can deal with MOT time.

Its a bit of an **** of a thing to change, so unless you've got a friendly MOT man then i'd be tempted to leave it, or perhaps graft in a universal cat underneath.
 
aragorn said:
Depends how you can deal with MOT time.

Its a bit of an **** of a thing to change, so unless you've got a friendly MOT man then i'd be tempted to leave it, or perhaps graft in a universal cat underneath.
Click to expand...

cheers mate ill have a look into it
 
Thanks all for all the replice :) it really help me alot without you guys help I would have gone to people that didn't knew anything about exhaust system :(

Ok long day for me today after cancelling the appointment with them Hays people I went to St Alban Top Gear after the check the car they said its no way you can run a singal cat on S4 they said it will make it unbalance and lose power what they recommend me is to remove the 2 under cats and leave the pro-cats and just run twin 2.5" pipes upto centre box then 3" all the way to back box and today all this was fixed :) plus my two flexi's was gone too :( so they fitted two new flexi's cost me extre £200 :(

Total all was £700 :(

It would have cost me £500 but because of the flexi's it cost me £700 :( but I hope it all worth the money so tomorrow is the remap :hubbahubba: lets see what would be the power output

The exhuast looks something like this:

1062_small.jpg
 
If you haven't had it done already do not use top Gear in St Albans. They are a PowerFlow agent. I've dealt with them a few times, they don't mandrel bend which means every bend in the sytem the pipe diameter decreases (not good for gas speed), the systems are not flow tested and the grade of stainless used is not a quality one so they still corode and rust. They also seem to like suggesting flexi pipes at every given oppertunity. They chopped my centre silencer out without adding the brace I suggested would be required to prevent the system twisting on the remaining rubbers. The guy was adament it would be fine without it and after just 15 miles the whole system had twisted on the rubbers as I thought it would. The following day they tried to tell me it was because of the standard flexi which was knackered which I suggested was ******** and if it was knackered it was due to the brace not being added which allowed the system to twist. I told the guy to weld the support brace in as I had suggested the previous day.

Really nice chaps in there and very friendly but I just can't recomend them
 
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£200 for a pair of flexis? that sounds VERY expensive to me. Could pick up a set of sport cats for that money, never mind a flexi joint!

Did you get any shots of the system under the car?

A lot of these cowboys make the system in one huge piece, which is damn annoying if you want to work on things under there. Be interesting to see what it looks like.
 
so did you have a milltek? or a long life as the long life exhausts round me also are a brand of topgear!
 
Oranoco said:
If you haven't had it done already do not use top Gear in St Albans. They are a PowerFlow agent. I've dealt with them a few times, they don't mandrel bend which means every bend in the sytem the pipe diameter decreases (not good for gas speed), the systems are not flow tested and the grade of stainless used is not a quality one so they still corode and rust. They also seem to like suggesting flexi pipes at every given oppertunity. They chopped my centre silencer out without adding the brace I suggested would be required to prevent the system twisting on the remaining rubbers. The guy was adament it would be fine without it and after just 15 miles the whole system had twisted on the rubbers as I thought it would. The following day they tried to tell me it was because of the standard flexi which was knackered which I suggested was ******** and if it was knackered it was due to the brace not being added which allowed the system to twist. I told the guy to weld the support brace in as I had suggested the previous day.

Really nice chaps in there and very friendly but I just can't recomend them
Click to expand...

Damn it I didn't know they were powerflow they called them self Flowtech :( any ways the system was done today and life guarante is on the system so anything goes wrong I will take them to court hehe :)

aragorn said:
£200 for a pair of flexis? that sounds VERY expensive to me. Could pick up a set of sport cats for that money, never mind a flexi joint!

Did you get any shots of the system under the car?

A lot of these cowboys make the system in one huge piece, which is damn annoying if you want to work on things under there. Be interesting to see what it looks like.
Click to expand...

I didn't take any pictures of it but I try to get some tomorrow if I could tomorrow but it does look almost same as the picture that I post.

S4twiggy said:
so did you have a milltek? or a long life as the long life exhausts round me also are a brand of topgear!
Click to expand...

I went for the long life one Top gear custom made.
 
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So far I am very happy with the system its very quite and its sounds very nice on higher Rev's and the car pulls very nice in any gears :) and the top Gear guy said I should look around 20 BHP increase but even if I get 15 BHP I would be happy :)
 
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Hey man, glad you're making headway... I'm 1) too broke to try to modify properly and 2)to much of a woose to modify incase I break it bad!
 
thats got to be really quite with the precats in and 2 boxes . Post up a vid if you can or some pics , do you get the sandblaster effect at high revs?
 
Ah well. As long as your happy.
Would take the power increases claimed with a pinch of salt. I'm still waiting to see one of their systems to make standard power never mind see an increase, Seen their systems lose power typically about 5bhp or so :(

Get it on the rollers and see what comes up. Hopefully you'll see a result your pleased with
 
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