rwdwiganer Posted January 18, 2013 Share Posted January 18, 2013 I have decided to get a full turbo back exhaust system made up but can't decide if to go 3.5" downpipe and system or would it be any benefit going 4" downpipe down to 3.5" back or will it really make bugger all difference under 600bhp? I don't want a full 4" turbo back system as I know it is complete overkill and don't want to be stuck on every speed bump as my FD is quite low! I keep getting mixed opinions on this! The turbo I ended up buying is a GT3582r with 0.82a/r T4 exhaust housing... Quote Link to comment Share on other sites More sharing options...
Guigsy Posted January 18, 2013 Share Posted January 18, 2013 The turbo will have a 3" port so going to 4" then down to 3.5 is pointless IMO. With that turbo 3" is fine. I have the same turbo and had a 4" system all the way through and it was crazy loud to the point driving the car was painfull. I still have a 4" down and mid but only because I couldn't be bothered to change it but now have a 3" twin box whifbitz exhaust. Much better. 3" should be fine for anything upto 600 according to Paul. Quote Link to comment Share on other sites More sharing options...
rwdwiganer Posted January 18, 2013 Author Share Posted January 18, 2013 I know 3" would probably be fine but surely if the price is pretty much the same, the larger downpipe would create less back pressure and more power? I don't want a 3" system but I am still undecided if to go 4" or 3.5" downpipe- I have pretty much made my mind up I will be going 3.5" system though. After seeing how well Nic's old Supra from on here with the 4" downpipe made power at only 1.3 bar I was thinking of doing something very similar with mine- but with standard cams and slightly more boost. Quote Link to comment Share on other sites More sharing options...
Nic Posted January 18, 2013 Share Posted January 18, 2013 TBH The only reason I went with a 4" downpipe and mid pipe was because there were no 3" or 3.5" ones in stock at the time. I had a 3.5" Greddy exhaust fitted, so there was probably little benefit having the 4" pipes, the 4" mid pipe needed to be modified to clear the brace underneath and because it used a v-band midpipe/exhaust flange ground clearance was not great over speed bumps. Doing it now I'd fit a 3.5" down/mid pipe with standard 2 bolt exhaust flange and I'd also have the waste gate recirculated back into the down pipe. Whichever size you go with you won't be disappointed with the response and power delivery. Quote Link to comment Share on other sites More sharing options...
rwdwiganer Posted January 18, 2013 Author Share Posted January 18, 2013 Thanks Nic, that is good to know :-) I just can't wait to get it up and running now! I will get pictures up as soon as the real work starts! Quote Link to comment Share on other sites More sharing options...
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