rbgtst33 Posted March 8, 2007 Share Posted March 8, 2007 hey ive got a 4inch stainless steel catback exhaust sitting in my garage jus waiting to get fitted, but ive been told that a 4" is too big and wont b as effective as a 3" exhaust. Whats the deal here, should i sell the 4" and look for a 3" or just chuck the 4" on. opinions anyone? Link to comment https://www.sau.com.au/forums/topic/159631-3inch-or-4inch/ Share on other sites More sharing options...
R33GOD Posted March 8, 2007 Share Posted March 8, 2007 hey ive got a 4inch stainless steel catback exhaust sitting in my garage jus waiting to get fitted, but ive been told that a 4" is too big and wont b as effective as a 3" exhaust. Whats the deal here, should i sell the 4" and look for a 3" or just chuck the 4" on.opinions anyone? depends on what u want. a 4 inch will give u good top end and average low to midrange and a 3 inch will give u good down low/ mid range power Link to comment https://www.sau.com.au/forums/topic/159631-3inch-or-4inch/#findComment-2964258 Share on other sites More sharing options...
pavel Posted March 8, 2007 Share Posted March 8, 2007 What turbo are you running? engine mods? Link to comment https://www.sau.com.au/forums/topic/159631-3inch-or-4inch/#findComment-2964259 Share on other sites More sharing options...
rbgtst33 Posted March 8, 2007 Author Share Posted March 8, 2007 stock turbo basically car is all stock except for a shitty pod which has to be changed and a dump pipe. Originally when i bought the car it had a turbo back exhaust fitted, 3inch from the turbo through to a 4inch from the cat, which is currently sittin in my garage because it had to be taken off for the roadworthy. Link to comment https://www.sau.com.au/forums/topic/159631-3inch-or-4inch/#findComment-2964304 Share on other sites More sharing options...
LiQuid IcE Posted March 8, 2007 Share Posted March 8, 2007 I thought when it came to turbo cars Biggger is Better. No exceptions. It's only NA's that require back pressure etc... But if its a road car then you have to wrry about police/EPA noise. Link to comment https://www.sau.com.au/forums/topic/159631-3inch-or-4inch/#findComment-2964329 Share on other sites More sharing options...
nisskid Posted March 8, 2007 Share Posted March 8, 2007 go 3.5, 3inch is really optimum for a balance between performance and sound, but 3.5inch is better for performance. Link to comment https://www.sau.com.au/forums/topic/159631-3inch-or-4inch/#findComment-2964414 Share on other sites More sharing options...
nisskid Posted March 8, 2007 Share Posted March 8, 2007 I thought when it came to turbo cars Biggger is Better. No exceptions.It's only NA's that require back pressure etc... But if its a road car then you have to wrry about police/EPA noise. i beleive if ur exhaust is too large on an exhaust u will lose alot of bottom end due to no backpressure etc, but for high revs, yes better flow will mean better performance. Link to comment https://www.sau.com.au/forums/topic/159631-3inch-or-4inch/#findComment-2964425 Share on other sites More sharing options...
Jdfnq Posted March 8, 2007 Share Posted March 8, 2007 3.5 works for me My HKS 3.5 sounds great and there seems to be no lag. no issues at ll Link to comment https://www.sau.com.au/forums/topic/159631-3inch-or-4inch/#findComment-2964446 Share on other sites More sharing options...
rbgtst33 Posted March 8, 2007 Author Share Posted March 8, 2007 ohk that helps, but is it worth goin to the effort to gettn rid of the 4" n finding a 3.5 or a 3" or would you guys just chuck on the 4" since its jus sittn in the garage. Link to comment https://www.sau.com.au/forums/topic/159631-3inch-or-4inch/#findComment-2964630 Share on other sites More sharing options...
R33GOD Posted March 8, 2007 Share Posted March 8, 2007 ohk that helps, but is it worth goin to the effort to gettn rid of the 4" n finding a 3.5 or a 3" or would you guys just chuck on the 4" since its jus sittn in the garage. just run the best of both worlds. run a 3inch front/ dump and 4 from the cat back if its already sittin there Link to comment https://www.sau.com.au/forums/topic/159631-3inch-or-4inch/#findComment-2964645 Share on other sites More sharing options...
GeeTR Posted March 8, 2007 Share Posted March 8, 2007 just run the best of both worlds. run a 3inch front/ dump and 4 from the cat back if its already sittin there Go biggest you can. Considering your current mild setup, keep the 4" cat back, grab a 3.5" Turbo > Cat section. If your planning big numbers later on, then a diff m.fold / turbo will require new front section anyway. - M Link to comment https://www.sau.com.au/forums/topic/159631-3inch-or-4inch/#findComment-2964757 Share on other sites More sharing options...
rbgtst33 Posted March 9, 2007 Author Share Posted March 9, 2007 orite cheers guys Link to comment https://www.sau.com.au/forums/topic/159631-3inch-or-4inch/#findComment-2968177 Share on other sites More sharing options...
SLIPPERY Posted March 9, 2007 Share Posted March 9, 2007 yeah a lot of funny information floating around with people saying youll lose performance with decreased back pressure lol . Yes, thats the theory with naturally aspirated motors any exhaust you have is gonna have more than enough back pressure since the gases have to pass through our little friend, the turbine wheel. as said by GeeTR, go the biggest you can Link to comment https://www.sau.com.au/forums/topic/159631-3inch-or-4inch/#findComment-2968229 Share on other sites More sharing options...
bigcarl Posted March 9, 2007 Share Posted March 9, 2007 mate,my r33 gts-t is running 3inch exhaust gt3040 600hp turbo ,24psi of boost and is making 346rwkws. i think 4 inch is a real over kill for your current application. Link to comment https://www.sau.com.au/forums/topic/159631-3inch-or-4inch/#findComment-2968946 Share on other sites More sharing options...
SLIPPERY Posted March 10, 2007 Share Posted March 10, 2007 well, hes got the 4 inch sitting there...might as well use it rather than fork out to get a 3 inch system made up Link to comment https://www.sau.com.au/forums/topic/159631-3inch-or-4inch/#findComment-2969306 Share on other sites More sharing options...
BHDave Posted March 10, 2007 Share Posted March 10, 2007 Even back pressure in NA cars is a myth. It has been proven that the gains in NA exhausts are made in the headers. Biggest pipe possible after that with the compromise being the noise. In this case. Chuck the 4 inch on, nothing to lose. If you don't like the noise then swap for a 3 inch. You may end up smack in the middle of the rich and retard mapping as a result with either a 4 inch or 3 inch though In bigcarls example I think you'll find there are gains to be had by going bigger, though it's not necessary by any stretch. Link to comment https://www.sau.com.au/forums/topic/159631-3inch-or-4inch/#findComment-2969394 Share on other sites More sharing options...
evlgtr Posted March 10, 2007 Share Posted March 10, 2007 i just got my exaust fitted and its 3 1/2 inch starting from dump pipse and i have a 3 1/2 inch high flow cat and it seems to be goin very well for me and iam running a standard rb26dett Link to comment https://www.sau.com.au/forums/topic/159631-3inch-or-4inch/#findComment-2970017 Share on other sites More sharing options...
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