When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I dont agree. The uppipe has a far bigger impact on spool as it comes directly from the headers, the exhaust is after the turbo so apart from allowing a little more timing towards higher revs, it makes little if any difference to spool. Adding a bell mouthed downpipe would help get the exhausted gases out too. It is down to personal preference rather than functionality for the high majority of users.
I disagree that the exhaust makes no difference to spool. My exhaust has an adjustable bung in the tailpipe to reduce the noise. When it's closed thus restricting the gas flow the car is not as responsive due to the turbo not spooling as quick!! When I open it the difference is night and day to me. Next time I do a rolling road shoot out I am going to do 2 power runs one with the bung closed and one with it open to see what hp difference there is.
PS my exhaust is a 3.5 inch de-cat system running at 440 bhp.
I didnt categorically say there was nothing, if there was though it was not overly detectable via logging nor during normal driving.
Replacing a cat equipped uppipe with a decat would give more in that area.
13 January 2013, 12:34 AM
