S3 Noise on Relentless Downpipe/Sport cat

sideways steve

Registered User
Hey folks, hoping others with this exhaust setup may be able to clarify something for me....

My S3 is stock apart from the Relentless/XSPower Downpipe and Sport Cat.

I had noticed since picking up the car it had a fairly "tinny" noise from the exhaust coming from around the gearstick area or possibly just in front of it and it was starting to annoy me.

Since my carpet is currently removed and drying out due to a water leak the noise is even more noticeable and I had always assumed it was just a leak somewhere.

At the weekend I managed to get time to take a look and sure enough the clamp joining teh CAT to teh rear section was loose as hell and you could wiggle the whole lot about.

I thought to myself, awesome Ill fix this and no more noise.............

Nope !

I fixed the leak and although the noise is not as bad theres still a very tinny/hollow noise from it. Is this just how this downpipe and cat sounds or am I possibly missing another leak further up, perhaps the downpipe to turbo gasket ?

If this is how this setup sounds then Ill be ripping it off and going back to stock setup i think as I hate cars that sound like they have a leaky exhaust !


12th Gear
i have a similar issue, had the XS DP and sports cat fitted end of december and at the time my mechanic said that the cat to cat back joining piece was leaking because the exhaust sealant he was using just got brittle and flaked off. Plan was to re-seal with heat proof silicone around now except i have noticed recently there is this noise coming from further up.
If i hang my head under the car while revving the engine a bit i can hear the cat to cat back bit leaking but there is definately a rattling noise coming from where the DP meets the cat.
I am going to get him to re-seal it all with heat proof silicone and hoepfully that will sort it but i think there is a heat shield or something rattling aswell.
What was used to seal your exhaust?


Registered User
Have exactly the same problem with my scorpion. Always had it. Been on and off like three times since and still makes a noise from same area. Mines hitting the tunnel where exhaust sits. Can tell it isn't sitting in the middle of the tunnel and three garages haven't been able to sort it. So am just dealing with it until some one can explain why.


Registered User
I have XS and de-cat and mine is tinny until warm then sounds fine. I thought the tinny noise was from the de-cat but I guess its the DP.


My other car is a MINI!!!!
I've heard a few ko4's with decats sounding like this, although always when using standard catback system.

On my daily I ran a downpipe and decat with the standard catback, and it sounded tinny and ****.

On my track car I ran a downpipe and decat into a milltek system, and it sounded great, not at all tinny.

I now have a cheap aftermarket catback on the daily, and it still sounds a bit tinny, but not SO bad.

Will update with how the ko4 sounds with the XS downpipe when I get it running! Although it does seem to be a feature of highly free flowing systems that they get a bit raspy.


Registered User
I'm picking up a spare standard S3 cat back system tonight that I got off eBay for £20. My plan is to do a DIY exhaust system, running 3" pipe into the box. It'll be interesting to see if that gets rid of the tinny noise.

sideways steve

Registered User
Cheers for the replies, it does deffo quieten a bit when it warms up so I had kinda thought it may just be a normal noise. I am just not used to it as on any of the jap stuff I have had normally anything with a turbo never had any rasp to it.

I think I may re seal everything anyway, I done the cat to centre section with high temp silicon and the genuine Audi clamp/sleeve arrangement as there was no doubt it was leaking but I didn't have time to check the joins further up as I was too busy sorting my heat shields and my headlight levelling system.

The actual exhaust is definitely not hitting anything and its not that sort of noise, its a raspy/tinny sound kind of like a slight exhaust leak. Actually it sounds a bit like most hondas when they have had an aftermarket system fitted..... angry wasps in a tin can ! LOL


S3 hunter
Mine exactly the same mate. I took mine apart again to double check again and it was fine. I even wrapped the downpipe in heat wrap to try and stop the raspy noise but its still there. Sooooo annoying.


Badger 5 Edition...Its all about the flow...
Staff member
3" exhausts are tinny... mine sounds very tinny on cold start... sounds deeper out the back and under boost :)



If In doubt, Flat out!
hmm... I thought I was the only one! I cut the standard cat element out of the pipe and re-sealed it, which caused this horrible tinny/waspy noise when cold (also a little bit when warm). So when changed to 3" and sports cat, hoped it would be cured. It still sounds s**t on cold start up for a few minutes. Once warm, sounds fine. Although, think mine may still be leaking very slightly from around the turbo.