What power shall I expect?

[HMS-S6]

I have to say, even on a new turbo, stem seals and breathers mine tended to smoke without a cat, but most don't have a problem

[dest]

Ive been running gutted cats for about 8 months now and have never seen a single puff of smoke atall

[Christophski]

I'm hoping for no smoke I alsoam hoping for a bit of extra oomph!

[Jamo]

I may be wrong - after all i can't fix my own S6 despite being a mechanic But i think what the guys are getting at is the only way to gain anything by means of an exhaust is to go 3" turbo back!?!?!?

You can get gains from replacing from cat back however the biggest gain on a turbo car is getting a bigger downpipe.

Most people are put off saying it's too noisey but IMO thats poppycock, the noise is down to the boxes put in the system.

I have 0 drone at any rpm on a full 3" system from tip to tail and it's not noisey in the car although it does have a distinct deep rumble

[Rusty]

Second that, a 3" DP is not loud, it's usually the free flowing sports silencers that are used that make the car loud!

[Christophski]

So if I was to get a 3" dp put onto the rest of the stuff I have, being standard size, would that increase hp slightly?

[Rusty]

Don't get too hung up on HP on the stock turbo, it's not something that's worth chasing, stock turbo is about low lag, lots of available torque low down and an easy to drive and maintain car. Persomally, my gains have been because I've been building my car to accept a something capable of 375-450bhp.

To answer your question, a 3" DP makes a small difference on a stock turbo but as the stock turbine is restictive, it's not like fitting a better exhaust to a bigger turbo car.

That said, my car goes well with the 3"/2.5" system and RS2 IC, even if both are not required, they do improve efficiency a little and add to the fun, I'm sure it'll go better still with the uprated bottom end, RS2 EM and flowed head - again pointless on a stock car - but it'll be ready for any turbo I want to fit to achieve my requirements then.

[mcandmar]

You may see gains in response / drive ability, but as Andy says dont get hung up on dyno peak HP numbers.

Cat bypass pipes made a really nice difference to mine, comes on boost quicker, and feels less restricted top end. It possibly made no difference whatsoever to peak HP, but its much nicer to drive.

Nothing is pointless

[dest]

Definitly dont bother fitting a 3" dp just to get more power, that sort of mod is done to help prepare for bigger power with other mods

[Christophski]

Ok. It's all on now n it is different but can't put my finger on how. It's powerflow as said before so sounds nice but hangs real low which is not good on a 30 mm lowered car. Gonna have to play with that as all I get is scrapeage no matter how small the bump. I'm thinking polly hangers and possibly cutting the bends, re angling them and re weld em on for more clearance