themodifiedkid Posted May 10, 2009 Share Posted May 10, 2009 Firstly lol Sorry if this is another boring thread people, I just want to make sure im not gonna fook up the engine. Anyway am I right in thinking that if you are only going to decat just one of the cats, the one to do is the first cat. I hope so as ive already ordered one:rolleyes: So basically ive got a jspec facelift tt and am looking at just replacing the first cat only, will this be safe to do, am i right in thinking by keeping the second cat in will act as a restrictor. Any help on this would be much appreciated. Just need to clear this up because some things i read and says decat first pipe and keep second and others safe decat 2nd pipe and keep first cat, which one is it? Quote Link to comment Share on other sites More sharing options...
AlanM Posted May 10, 2009 Share Posted May 10, 2009 My second one was out first, then the first one came out second Quote Link to comment Share on other sites More sharing options...
themodifiedkid Posted May 10, 2009 Author Share Posted May 10, 2009 Ok, still no clearer lol... Just need to know if this is safe just to decat first pipe Quote Link to comment Share on other sites More sharing options...
Scooter Posted May 10, 2009 Share Posted May 10, 2009 am i right in thinking by keeping the second cat in will act as a restrictor. yes it will, but you need to consider the whole exhaust system. You can decat fully and have a stock cat back exhaust and probably not over boost but as you know add a non standard exhaust and it will almost certainly overboost. Most TT's will be in the safe range of boost with only one cat out and an aftermarket exhaust but you should have a boost guage installed really.......and if you do i'd install it prior to decatting then if it isn't the best/accurate guage in the world you should at least see how much it goes up post decat. Quote Link to comment Share on other sites More sharing options...
themodifiedkid Posted May 10, 2009 Author Share Posted May 10, 2009 yes it will, but you need to consider the whole exhaust system. You can decat fully and have a stock cat back exhaust and probably not over boost but as you know add a non standard exhaust and it will almost certainly overboost. Most TT's will be in the safe range of boost with only one cat out and an aftermarket exhaust but you should have a boost guage installed really.......and if you do i'd install it prior to decatting then if it isn't the best/accurate guage in the world you should at least see how much it goes up post decat. Thanks for the reply. Ive already installed an apexi boost gauge which seems to read what stock boost is supposed to be so it is accurate, and im running on a HKS silent hi power cat back exhaust. Quote Link to comment Share on other sites More sharing options...
dan4 Posted May 11, 2009 Share Posted May 11, 2009 Replied to your pm buddy.... Il test the boost gauge and i can use mine to test anyhow as i know its spot on Id say the first one would be the best to get out of the way first as the second is easy to get to anyway if you change your mind, plus you will not build up as much heat with no first cat. Ideal situation is remove both cats and use restriction to get it close to stock, then ease it up to where you want. Gives you a consistent boost level regardless of air temps Quote Link to comment Share on other sites More sharing options...
themodifiedkid Posted May 11, 2009 Author Share Posted May 11, 2009 Replied to your pm buddy.... Il test the boost gauge and i can use mine to test anyhow as i know its spot on Id say the first one would be the best to get out of the way first as the second is easy to get to anyway if you change your mind, plus you will not build up as much heat with no first cat. Ideal situation is remove both cats and use restriction to get it close to stock, then ease it up to where you want. Gives you a consistent boost level regardless of air temps Nice one cheers buddy, very much appreciated. I will put the first decat in for now(when it turns up, and after my mot next week) then more than likely go full decat soon after:eyebrows: Quote Link to comment Share on other sites More sharing options...
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