[quote="Grimketel"] Those headers belong on a 1930's russian farm tractor.
quote]


I dont think theres much of a difference between a 1930's russian farm tractor and a new one IMHO... Theyre still s**t.

He's saying to put a 30ish cm long bit of 2.5" pipe between the headers and cat, so your cat is approximately 30cm further towards the back of the car. Then use a 3" cat and catback (catback will have to be altered as will need to be around 30cm shorter before the diff).

I haven't seen this set up but have seen headers where the secondaries were really long and effectively did the same thing, minus any tuning benefits as a result of the headers used. Only problem is your cat becomes less efficient as temperature drops, how much difference there is in temp and how this affects emissions I'm not sure...

Yeah that way if you go supercharged later on all you need to do is replace the short 2.5 pipe with a 3inch one.

thanks for the explanation fellas.
tickford - Im already running a s/c but only have a 2.5" mandrel system now and I have been told to modify the collector on the headers to a 3" then cat and 3" system after. But if I can get the same sort of benefits with w 30cm pipe with flange then cat at 3" system without modifying the collector on the headers and still have a good gain power wise, then I'll try that instead.

I just realised this thread was from before it was S/C...

Seeing as you are over 200rwkw and I am assuming you want to increase that just go 3" all the way. I had a mind blank and didn't realise what car it was on.

Sorry i didn't realise it already had a blower on it. Just put the 3inch system on it. I wouldn't worry about moding the collector to 3 inch, just go straight from the collector to a 3 inch pipe.
that gain wouldn't be worth the effort.

Awesome, will do. Im also in 2 minds as to whether or not I should also go down the same path TROYMAN has and convert the s/c to turbo. Hmm, thats a subject to be discussed in another thread.