supra_si Posted April 5, 2009 Share Posted April 5, 2009 2.5" or 3" 2nd decat pipe is better for a TT? ta muchly Quote Link to comment Share on other sites More sharing options...
hadyn Posted April 5, 2009 Share Posted April 5, 2009 Either. With a 3" you might scrape the odd speedbump every now and again... Quote Link to comment Share on other sites More sharing options...
tDR Posted April 5, 2009 Share Posted April 5, 2009 2.5". The more free flowing you make it, the more likely you are to overboost and require an even smaller diameter restrictor ring. Cheers, Brian. Quote Link to comment Share on other sites More sharing options...
Guest drlee Posted April 5, 2009 Share Posted April 5, 2009 sorry if i sound like a div but wouldnt it b better,to go 3 inch,no restrictor ring,then use a good boost controller,i did this to one and used aem true boost,it was perfect,i now use aem true boost on my own, d.r Quote Link to comment Share on other sites More sharing options...
supra_si Posted April 5, 2009 Author Share Posted April 5, 2009 well i still have the first cat in place so wont need a restrictor ring, the rets of my pipework from the second cat at the moment if 3" thats all Quote Link to comment Share on other sites More sharing options...
tDR Posted April 5, 2009 Share Posted April 5, 2009 sorry if i sound like a div but wouldnt it b better,to go 3 inch,no restrictor ring,then use a good boost controller,i did this to one and used aem true boost,it was perfect,i now use aem true boost on my own, d.r A boost controller cannot lower boost, only raise it. You're asking for trouble like that. Quote Link to comment Share on other sites More sharing options...
tDR Posted April 5, 2009 Share Posted April 5, 2009 well i still have the first cat in place so wont need a restrictor ring, the rets of my pipework from the second cat at the moment if 3" thats all A bit pointless only doing half a decat job IMO - to really see the benefits you need to remove the huge blockage that is the stock cats. 2.5" pipework mates to 3" just fine. I have this setup on mine, 2.5" decats to Blitz Nur Spec R cat back 3", and it's in no way a restriction at BPU+++ levels (check my 1/4 times!). The restriction is the stock turbos. Cheers, Brian. Quote Link to comment Share on other sites More sharing options...
Scott Posted April 5, 2009 Share Posted April 5, 2009 A boost controller cannot lower boost, only raise it. You're asking for trouble like that. Is this not in the faq yet? lol In fairness i think this is one of the first times this has raised its head in a while Back to the original query, i always go for 3" everything.... just in case i decide to "upgrade" later in life. One less thing to worry about. As said though, get a 1bar restrictor ring and a boost controller to do it properly. If you get 3" everything and then a 1.2bar restrictor ring it won't be an exact science Quote Link to comment Share on other sites More sharing options...
supra_si Posted April 5, 2009 Author Share Posted April 5, 2009 ahh right cheers guys, not keen on doing the first cat yet i know its the bigger PITA and not confident doing it myself so just going to get second one done for now. Quote Link to comment Share on other sites More sharing options...
tDR Posted April 5, 2009 Share Posted April 5, 2009 Is this not in the faq yet? lol In fairness i think this is one of the first times this has raised its head in a while I vaguely recall going into detail on how turbo systems work / why J specs overboost and why you can't lower the boost with an EBC on one of the threads - a good one to search for drlee. i always go for 3" everything.... Bet the wife is disappointed!!! just in case i decide to "upgrade" later in life. One less thing to worry about. As said though, get a 1bar restrictor ring and a boost controller to do it properly. If you get 3" everything and then a 1.2bar restrictor ring it won't be an exact science Not a lot of point in the 3" decats as I said earlier - you end up with more overboosting and a bigger slag of a mod restrictor ring to fudge fix it, and it's not really futureproofing since going single requires a bespoke downpipe / decat anyways to mate with your cat back exhaust. Cheers, Brian. Quote Link to comment Share on other sites More sharing options...
Scott Posted April 5, 2009 Share Posted April 5, 2009 Bet the wife is disappointed!!! Walked into that one lol Not a lot of point in the 3" decats as I said earlier - you end up with more overboosting and a bigger slag of a mod restrictor ring to fudge fix it, and it's not really futureproofing since going single requires a bespoke downpipe / decat anyways to mate with your cat back exhaust. Cheers, Brian. Damn, forgot about that. Thats a very good point, if you go single you will need a custom DP anyway lol. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.