gogo Member of team Kittens Member 609 Member For: 20y 9m 9d Location: Melbourne Posted 27/09/06 01:44 AM Share Posted 27/09/06 01:44 AM Just for the record - a single 3" is more restrictive than the stock twin 2.25" pipe config...If mufflers and cat are better exhaust system as a whole might flow better, but why go backwards in some areas unless you are only after a change in exhaust note - if you change exhaust twin 2.5" or 3.5" are minimums.This may be why the 3" doesn't result in going into limp - because it does not aid flow (at least not meaningfully)The ECU's are very smart in these cars - particularly in the BF's so be careful what you do...First step should be the Edit with all mods IMHO.good luck! Ben. Link to comment Share on other sites More sharing options...
Fat-Tony Member 5,364 Member For: 18y 8m 11d Posted 27/09/06 03:14 AM Share Posted 27/09/06 03:14 AM gogo do you have any testing to support this, dyno charts flow tests ect? I would be interested in the results or is it just here say? Link to comment Share on other sites More sharing options...
bugster70 Donating Members 1,326 Member For: 19y 6m 29d Location: Canberra Posted 27/09/06 03:41 AM Share Posted 27/09/06 03:41 AM I would imagine it's just simple physics. Without getting my calculator out, you'll probably find that the combined cross-sectional area of two 2.5" pipes is greater than that of a single 3" one. Area of a circle is pi (approx 3.14) x radius squared. Now, where's my calculator... Link to comment Share on other sites More sharing options...
2fardown Member 526 Member For: 19y 6m 20d Gender: Male Location: Brisbane Posted 27/09/06 03:51 AM Share Posted 27/09/06 03:51 AM X-force will be releasing a new exhaust for Cars with 280RWKW plus, it will be a 4inch dump off the turbo with 4 inch cat, then a single 3.5 system with either dual mufflers or single muffler out the back, should be ready in a few weeks and will be less then most of the complete systems out there.the price of there 3inch system has dropped to $1250 installed and is good for stock cars, go to www.bestmufflers.com←It's already released. Saw one this morning. They look pretty flash.To the thread starter: Don't even bother. You;re worried about voiding your warranty and you want to change your cat? This will void your warranty anyway.Fit a K&N filter and wait till your warranty expires. Link to comment Share on other sites More sharing options...
jordak Member 1,226 Member For: 20y 5m 23d Posted 27/09/06 04:01 AM Share Posted 27/09/06 04:01 AM After running the stock system (centre muffler mod) with an edit I changed to a 3" xforce system and would have to say that there was an improvement in low - midrange power however not enough to justify the $1,100 outlay.A subsequent custom tune returned little improvement however this was found to be due to the xforce cat not being any better than the stocky. Once that was sorted the system has not held me back, although I'm only running around 260rwkw in an attempt to preserve the auto.As far as a 3" system being a step backwards from the stock twin 2 1/4inc I don't know however up to now noone has been able to tell me the flowrate of twin 2 1/2 pipes compared to a single 3" system that apparently flows @ around 750cfm which is better than most cats anyway. Some also hold the view that a single system is better matched to a turbo than a twin system.The problem with the stock system is that in addtion to the cat needing replacement the centre mufflers are not straight through (compared to the 3" xforce) hence they are also a restriction, which is why the tuning houses recommend their removal. The other consideration is the sound and in my opinion the 3" xforce has a far better sounding note than the stocky with the centre muffler removed I.e. quieter / deeper on cruise and angrier on full noise. You also don't get that burble fart burble sound on back off which did my head in after a while, too ricey.If I was to do it all again I would spend $1,200 or so on the new xforce 3 1/2" system (they use better cats now) as it will be adequate for most power levels, is a well made system, without the drone and or noise levels of a 4" system.To modify the stock system could cost you up to $700 by the time you buy a decent cat / centre muffler set up (hotdogs) and labour to weld in new cat and installation. Bearing in mind that you now no longer have the totally stock system to put back on the car or a second hand well built xforce system to sell of recover the cost difference. Link to comment Share on other sites More sharing options...
ROLMDL role model Member 1,111 Member For: 18y 8m 22d Gender: Male Location: Melbourne,S.E Posted 27/09/06 04:16 AM Share Posted 27/09/06 04:16 AM were can I get a XFORCE exhaust system from? Link to comment Share on other sites More sharing options...
DBOSS Faster than any BTA,XTC,Autotech, Nizpro and Tunehouse car Member 3,918 Member For: 21y 5m 10d Location: D SHIRE! Posted 27/09/06 04:24 AM Share Posted 27/09/06 04:24 AM No point in putting a 3" system on as the factory system flows to 3 1/4" Link to comment Share on other sites More sharing options...
F6 UTE - Track Bound EVO III - Member 3,367 Member For: 19y 11m 17d Gender: Male Location: Strapped in and holding on Posted 27/09/06 07:30 AM Share Posted 27/09/06 07:30 AM I'm running 4" dump ( no real gains there, just a bit of response ) no cat and no centre muffler. Stock 2.5" piping all the way, factory rear muffler.. Flows with no issues.Get an edit, gains will be more than exhaust anyway. sound?? who cares, you'll be going faster. Link to comment Share on other sites More sharing options...
F6 UTE - Track Bound EVO III - Member 3,367 Member For: 19y 11m 17d Gender: Male Location: Strapped in and holding on Posted 27/09/06 07:31 AM Share Posted 27/09/06 07:31 AM No point in putting a 3" system on as the factory system flows to 3 1/4" ←^^^ I agree with Captain Caveman.. Link to comment Share on other sites More sharing options...
Fat-Tony Member 5,364 Member For: 18y 8m 11d Posted 27/09/06 08:15 AM Share Posted 27/09/06 08:15 AM No point in putting a 3" system on as the factory system flows to 3 1/4" ←^^^ I agree with Captain Caveman..←Im inclined to agree as the outlay for a new system isnt worth it unless your doing big mods. But what about where the stock system splits into 2, there would be some sort of power sucking turbulance there. Link to comment Share on other sites More sharing options...
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