Another exhaust thread...

[Max Read]

hi guys, I think it's been covered before but I'm struggling to find it. Basically I know BCS are the way to go for build quality etc.

At what sort of power do the cobra/miltek etc exhausts become restrictive as they reduce to 2.75" instead of the 3" BCS all the way through?

 

[prt57]

The catback is not the restrictive part. The downpipe is the part that saps power.
APR say that one of their downpipes can be joined to a standard cat back and a TTE 420 turbo will still produce 400 BHP. I would say that the BCS downpipe will flow better than the APR so no problems there.

 

[Kurt]

Cat backs are slightly restrictive, had mine on the rollers then fitted a scorpion cat back then back on the rollers with a 16bhp gain

 

[prt57]

A slight update, my son's TTS has just been for a stage 2+ map at R-Tech and it made 262 BHP 284 ft lbs with the standard cat back coupled to a a BCS downpipe. It might have might have produced a slightly higher BHP with the full system but would you feel it and is it worth the extra £950?

I think trying to find the best value for performance is important.

When I was at Awesome I asked how much it would be to upgrade my S3 currently at APR stage 2+ To have a TTE 420 and associated goodies plus APR software. It would have been about £5k. I know it can be done cheaper is it really worth it?

 

[S3Alex]

A slight update, my son's TTS has just been for a stage 2+ map at R-Tech and it made 262 BHP 284 ft lbs with the standard cat back coupled to a a BCS downpipe. It might have might have produced a slightly higher BHP with the full system but would you feel it and is it worth the extra £950?

I think trying to find the best value for performance is important.

When I was at Awesome I asked how much it would be to upgrade my S3 currently at APR stage 2+ To have a TTE 420 and associated goodies plus APR software. It would have been about £5k. I know it can be done cheaper is it really worth it?

Totally agree re value related performance.

I think the trick is getting the right compromise,as it's easy to buy cheap and then have to spend again to get the job done right,or get the performance you wanted.

I don't necessarily think that a full exhaust system at an extra £950 is good value for a few percent more at Stg2,but if you're going further,then it does make a lot of sense.
For instance the Milltek I had on the car was clearly restricting the engine on it's last build,and made throwing that away and moving to a custom 90mm system a worthwhile job,but it had done well up until that point.

 

[Max Read]

Totally agree re value related performance.

I think the trick is getting the right compromise,as it's easy to buy cheap and then have to spend again to get the job done right,or get the performance you wanted.

I don't necessarily think that a full exhaust system at an extra £950 is good value for a few percent more at Stg2,but if you're going further,then it does make a lot of sense.
For instance the Milltek I had on the car was clearly restricting the engine on it's last build,and made throwing that away and moving to a custom 90mm system a worthwhile job,but it had done well up until that point.

At what point did the milltek become restrictive? What power were you putting out?

 

[S3Alex]

At what point did the milltek become restrictive? What power were you putting out?

At around 500bhp it was a problem.

Into the 500s it became so restrictive it was causing problems on the dyno but it's not really a criticism of a system that was never designed with that power in mind,just a limitation.
The bore of the system is a limitation,plus the backbox.

With the current mods,inc the turbo,the engine runs more efficiently and cooler.

 

[Max Read]

Wicked stuff, so it really isn't necessary unless going for a big turbo build!

 

[S3Alex]

Wicked stuff, so it really isn't necessary unless going for a big turbo build!

I'd agree but still have to say that the build quality of the BCS is something else

 

[audismart]

I hear what Alex says about flow in an exhaust,
I was stage 1 on Sunday with my car being ready for stage2 this week. its a fwd 2.0tfsi k03 dsg, with a BCS Powerflow that I picked up 2nd hand, the benefits of the BCS is a fair bit of low down torque which helps before spinning up the smaller turbo.
On an AUTOBAHN on sunday I was pitted against an S3 with stage2+ manual, well lets just say he was only just getting away from me at 140.
I`m now stage 2 and getting ready for 2+, I`m never going to be an S3 stage 2+beater, but I will chomping at there heals due to power/weight ratios, but as Alex says flow is a very important factor in performance, so I will be concentrating on flow to and from the turbo next..

 

[Max Read]

From what I hear aswell, the extra couple hundred £ for a Bcs is a no brainer! I'm still debating the noise levels of a decat system with the power valve vs the resonated. If anyone has any comparisons would be ideal! Want to keep it relatively civil noise wise.

 

[prt57]

When I was at BCS last week Nige showed me the sports cat and it is large compared to others I have seen. Consequently, he told me that it has a higher flow rate than a decat. A decat is noisy.

 

[KentKid]

Morning all,

Like prt57, I also had a conversation with @BCS Nige a while back, and he explained that the 200 Cell Cat they use gives a true ratio of 85mm - so a greater flow rate area than a 76mm Cat delete.

Max Read - it's also worth considering the potential insurance/MOT issues that you might encounter running a Decat exhaust system.

 

[audismart]

From what I hear aswell, the extra couple hundred £ for a Bcs is a no brainer! I'm still debating the noise levels of a decat system with the power valve vs the resonated. If anyone has any comparisons would be ideal! Want to keep it relatively civil noise wise.

You'll be looking at the BCS WRC powervalve system then.