alex2jz Posted November 24, 2010 Share Posted November 24, 2010 Chaps i need your advice. I'm planning to get an aftermaket exhaust. I will most likely go NA-TT next year (finally decided ) but until then i need a change. My question is what exhaust to get 3" or 2.5" ? I will still be using my car with the NA engine more than an year now, MOT is coming... What's the best compromise ? I just want to get one exhaust which i can use with bot engines. Will the NA engine with a 3" exhaust have backpressure issues ? will it be obnoxiously loud (both cats in) ? What are the consequences of a TT engine with a 2.5" exhaust fitted ? I want to know Cheers Alex Quote Link to comment Share on other sites More sharing options...
adnanshah247 Posted November 24, 2010 Share Posted November 24, 2010 an NA is stupidly loud. i had a blitz nur spec R on my tt and single and it wasnt as loud as my mates NA (same exhaust). i didnt like being a passenger in the NA, the noise honestly does your head in. Quote Link to comment Share on other sites More sharing options...
alex2jz Posted November 24, 2010 Author Share Posted November 24, 2010 an NA is stupidly loud. i had a blitz nur spec R on my tt and single and it wasnt as loud as my mates NA (same exhaust). i didnt like being a passenger in the NA, the noise honestly does your head in. Cheers mate. Was your friends NA decated ? Quote Link to comment Share on other sites More sharing options...
Dnk Posted November 24, 2010 Share Posted November 24, 2010 2.5" is the way to go on the NA but not for a TT, i'd save your cash and just wait till you've gone TT and fit a 3" system on that when your doing the conversion, makes much more sense money wise if your going TT next year. Quote Link to comment Share on other sites More sharing options...
KamaSupra Posted November 24, 2010 Share Posted November 24, 2010 I've got a HKS Hi-power which is 3" pipework and a 3" decat pipe fitted too but I still find it fairly quiet. Is it because it's an auto? Quote Link to comment Share on other sites More sharing options...
Nic Posted November 24, 2010 Share Posted November 24, 2010 You won't lose any power fitting a TT exhaust, it will be loud though (especially if it is decatted as well) as they usually have just a single silencer, aftermarket NA exhausts tends to have an additional silencer on the mid pipe. Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted November 24, 2010 Share Posted November 24, 2010 Kind of depends what sort of power you're going for once N/ATT? if you're not going much over 360-380 then you can get away with a 2.5" remember that the std TT is 2.5", i also suspect that the N/A will suffer with a 3" system, and its nothing to do with back pressure, its about reversion, a larger bore will change the characteristic's. Quote Link to comment Share on other sites More sharing options...
alex2jz Posted November 24, 2010 Author Share Posted November 24, 2010 Cheers guys. Thinking of a 2.5" Even though it seems there can be no real compromise.. Probably will sell the 2.5" when the time comes. Quote Link to comment Share on other sites More sharing options...
Kirk Posted November 24, 2010 Share Posted November 24, 2010 i also suspect that the N/A will suffer with a 3" system, and its nothing to do with back pressure, its about reversion, a larger bore will change the characteristic's. I run a tanabe touring which is a 3" cat back with no issues with mine Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted November 24, 2010 Share Posted November 24, 2010 I run a tanabe touring which is a 3" cat back with no issues with mine Did you dyno it before and after, i would be surprised if you haven't lost a bit of mid range torque. Quote Link to comment Share on other sites More sharing options...
bignum Posted November 24, 2010 Share Posted November 24, 2010 Did you dyno it before and after, i would be surprised if you haven't lost a bit of mid range torque. Doubt that, the guy can torque for england:p Quote Link to comment Share on other sites More sharing options...
Kirk Posted November 24, 2010 Share Posted November 24, 2010 Did you dyno it before and after, i would be surprised if you haven't lost a bit of mid range torque. To be fair i didnt realy try out the stock exhaust anyway so i dunno whether there is much difference. Of all the NA's ive drove with 2.5s catbacks dont feel as quick but that maybe just me. Bare in mind i have 2 silencers in line and all pipework prior to the catback is 2.5". Im eventualy going to get it down to ryan for a going over like daryll did. Doubt that, the guy can torque for england:p Yarp yarp yarp Quote Link to comment Share on other sites More sharing options...
dangerous brain Posted November 24, 2010 Share Posted November 24, 2010 If you keep the cats you should be alright. Perhaps a restrictor ring AKA J-spec BPU could help out with the back pressure. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted November 24, 2010 Share Posted November 24, 2010 Why do people confuse back pressure (bad) with tuned resonance length (usually good) when speaking of N/A exhaust systems? My advice would be to leave the exhaust as it is and decide what to do when you make the conversion. Quote Link to comment Share on other sites More sharing options...
Steve A Posted November 24, 2010 Share Posted November 24, 2010 an NA is stupidly loud. i had a blitz nur spec R on my tt and single and it wasnt as loud as my mates NA (same exhaust). i didnt like being a passenger in the NA, the noise honestly does your head in. id agree with that i have a 3 inch TT exhaust on my NA (not sure what brand as it came with the car) and its far to loud for day to day use in my opinion will be changing it soon Quote Link to comment Share on other sites More sharing options...
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