AndrewOW Posted March 15, 2008 Share Posted March 15, 2008 I should say that I have a double de-cat at the moment, and would consider a sport cat if I knew that it wouldn't be too restrictive and affect BPU's performance gains etc. As my MOT will be coming up again soon, I think it may be worth getting one to save having to mess about each time. Quote Link to comment Share on other sites More sharing options...
Mike M Posted March 15, 2008 Share Posted March 15, 2008 Guys, dunno if this helps, but when I had my first cat in, without a RR, the car boosted to over 1.3 bar sometimes. Now with a 1.2 RR in, its always steady at 1.2bar, even in the cold. Therefore I guess putting a high flow cat in, wont negate the need for a RR. I think it depends on how restrictive your exhaust is or in other words how loud it is. When i still had only my 1st cat in the car held 0.9bar steady. Quote Link to comment Share on other sites More sharing options...
DannoSupra Posted March 16, 2008 Share Posted March 16, 2008 I dont think he's got the Supra anymore! Quote Link to comment Share on other sites More sharing options...
Chris and Alana Posted March 16, 2008 Share Posted March 16, 2008 I have a first decat, kept the original second cat and have a nur spec R and I found it overboosted to 1.3+ bar. The second cat doesnt seem very restrictive at all from my experiance so it may be worth experimenting with the stock cat to start with rather than forking out 350+ on a sports cat. I was/am going to use a rr with the stock second cat to restrict boost to 0.8-0.9 bar (instead of 1.2bar as it is now) and then use an EBC to increase boost as desired just like your idea but hopefully without the additional cost Quote Link to comment Share on other sites More sharing options...
SUPRASUZUKI Posted March 18, 2008 Share Posted March 18, 2008 Iirc a cat is now mandatory to go to the Nring as of January 2008 so if you have planned to go then it may be a wise investment. Gaz, did you find out if this is correct? Quote Link to comment Share on other sites More sharing options...
Gaz Walker Posted March 18, 2008 Share Posted March 18, 2008 I could have our Envy de-cats modified with sports cat fitted. Adds £100 on top of the cost for a good quality stainless decat. So that would be a full sports cat for £350. Quote Link to comment Share on other sites More sharing options...
Burna Posted March 18, 2008 Share Posted March 18, 2008 I could have our Envy de-cats modified with sports cat fitted. Adds £100 on top of the cost for a good quality stainless decat. So that would be a full sports cat for £350. Would that be in the second decat pipe Gaz? Would fit Jap and UK then perhaps Quote Link to comment Share on other sites More sharing options...
Ady Posted March 18, 2008 Author Share Posted March 18, 2008 Hi Lads - I havent got the Sup any more so am no longer in need of one of these Quote Link to comment Share on other sites More sharing options...
Gaz Walker Posted March 18, 2008 Share Posted March 18, 2008 Would that be in the second decat pipe Gaz? Would fit Jap and UK then perhaps It would be a first J-spec de-cat and 2nd sports cat yeah so would work on all cars. For just the rear pipe it would be around £230. Regards, Gaz. Quote Link to comment Share on other sites More sharing options...
Burna Posted March 18, 2008 Share Posted March 18, 2008 I don't think that's a bad price at all Gaz Quote Link to comment Share on other sites More sharing options...
AndrewOW Posted March 18, 2008 Share Posted March 18, 2008 It would be a first J-spec de-cat and 2nd sports cat yeah so would work on all cars. For just the rear pipe it would be around £230. Regards, Gaz. If thats the price for a Sports Cat in place of the 2nd de-cat, then that sounds almost perfect! MOT proof? Will it still require a restrictor ring on J-Specs though? Quote Link to comment Share on other sites More sharing options...
Ady Posted March 18, 2008 Author Share Posted March 18, 2008 If thats the price for a Sports Cat in place of the 2nd de-cat, then that sounds almost perfect! MOT proof? Will it still require a restrictor ring on J-Specs though? Id say its MOT proof - thats what the whole point of the thread was about for me. And id personally sitck with a RR, or run the risk of anayalating you sports cat Quote Link to comment Share on other sites More sharing options...
Gaz Walker Posted March 18, 2008 Share Posted March 18, 2008 If thats the price for a Sports Cat in place of the 2nd de-cat, then that sounds almost perfect! MOT proof? Will it still require a restrictor ring on J-Specs though? If I get someone goes for it, I can stick one on a Supra and get a result off our MOT gas analyser. It may still require a ring. This is a just a concept at the moment for the Supra but it would take very little to do as I have jigs for the pipes and sports cats in stock. Regards, Gaz. Quote Link to comment Share on other sites More sharing options...
AndrewOW Posted March 18, 2008 Share Posted March 18, 2008 If I get someone goes for it, I can stick one on a Supra and get a result off our MOT gas analyser. It may still require a ring. This is a just a concept at the moment for the Supra but it would take very little to do as I have jigs for the pipes and sports cats in stock. Regards, Gaz. Personally I would give it a go, but we're at the opposite ends of the country to do that easily Quote Link to comment Share on other sites More sharing options...
Gaz Walker Posted March 18, 2008 Share Posted March 18, 2008 Personally I would give it a go, but we're at the opposite ends of the country to do that easily True. I can send you one down, but I'd like to test it here first really! Gaz. Quote Link to comment Share on other sites More sharing options...
4packet Posted March 18, 2008 Share Posted March 18, 2008 I'm confused regarding the need for a sports cat. The OEM 2nd cat running with a 1st decat doesn't provide enough restriction to hold safe boost on a J-spec TT, therefore what is the requirement for a free flowing (sports) cat? I've had to fit my 2nd cat back in over the winter (and imminent MOT) to compensate for the colder climate as it was overboosting with a 1bar(?) restrictor ring. It still makes around 1bar boost atm. If come Summer time and I need to up the boost I would just file the RR out/remove to compensate (should I wish to keep the Cat in place for the Ring). Quote Link to comment Share on other sites More sharing options...
Ady Posted March 18, 2008 Author Share Posted March 18, 2008 I'm confused regarding the need for a sports cat. The OEM 2nd cat running with a 1st decat doesn't provide enough restriction to hold safe boost on a J-spec TT, therefore what is the requirement for a free flowing (sports) cat? I've had to fit my 2nd cat back in over the winter (and imminent MOT) to compensate for the colder climate as it was overboosting with a 1bar(?) restrictor ring. It still makes around 1bar boost atm. If come Summer time and I need to up the boost I would just file the RR out/remove to compensate (should I wish to keep the Cat in place for the Ring). Your answer is in your reply. Purley and simpley to pass MOT's without the hassle of faffing about adding and removing cat's ect the day before shes due to be MOT'd. There was a VOSA van arround here not so long ago, checking emissions ect ect..... The location of the sports cat would not be far off the position of the first cat, and taking out the second cat compleatley. A free flowing sports cat SHOULD provide sufficient back pressure, and keep you on the legal side. Quote Link to comment Share on other sites More sharing options...
Sandy-m2 Posted March 18, 2008 Share Posted March 18, 2008 Gaz, Would you take an exchange of a 2nd decat pipe into account? Thanks S Quote Link to comment Share on other sites More sharing options...
Ady Posted March 18, 2008 Author Share Posted March 18, 2008 Gaz, Would you take an exchange of a 2nd decat pipe into account? Thanks S When I planned on this I planed for the sports cat to replace the first cat, and having the second cat removed. I dont know if it would be as efficient if it was to replace the second cat and have the first cat bypassed with a decat pipe? Quote Link to comment Share on other sites More sharing options...
Gaz Walker Posted March 18, 2008 Share Posted March 18, 2008 Gaz, Would you take an exchange of a 2nd decat pipe into account? Thanks S I couldn't sorry Sandy, I don't deal in second hand parts at all. You'll get a buyer no problem on here or on Ebay Gaz. Quote Link to comment Share on other sites More sharing options...
Sandy-m2 Posted March 18, 2008 Share Posted March 18, 2008 Just thinking i'd be willing to be your test bunny - just going to purchase a exhaust in the next couple of days. Quote Link to comment Share on other sites More sharing options...
4packet Posted March 18, 2008 Share Posted March 18, 2008 Your answer is in your reply. Purley and simpley to pass MOT's without the hassle of faffing about adding and removing cat's ect the day before shes due to be MOT'd. There was a VOSA van arround here not so long ago, checking emissions ect ect..... The location of the sports cat would not be far off the position of the first cat, and taking out the second cat compleatley. A free flowing sports cat SHOULD provide sufficient back pressure, and keep you on the legal side. Wasn't convinced I had a question?? The 2nd cat does not appear to be much of a restriction, hence on a J-spec TT car where you need to run with a restriction in the exhaust, why would you bother with a free flowing cat and then stick a dirty plate infront of it to hold back boost? The only reason I can see to remove the 2nd cat is if the cat will overheat and the ceramic begins to break up at BPU power. Quote Link to comment Share on other sites More sharing options...
Gaz Walker Posted March 18, 2008 Share Posted March 18, 2008 Just thinking i'd be willing to be your test bunny - just going to purchase a exhaust in the next couple of days. OK cool. Let me know Quote Link to comment Share on other sites More sharing options...
Ady Posted March 18, 2008 Author Share Posted March 18, 2008 Wasn't convinced I had a question?? The 2nd cat does not appear to be much of a restriction, hence on a J-spec TT car where you need to run with a restriction in the exhaust, why would you bother with a free flowing cat and then stick a dirty plate infront of it to hold back boost? The only reason I can see to remove the 2nd cat is if the cat will overheat and the ceramic begins to break up at BPU power. This is why I created the post in the first place. To see if a single sports cat without a RR would provide sufficient back pressure to handle bpu AND keep it on the legal side Quote Link to comment Share on other sites More sharing options...
4packet Posted March 18, 2008 Share Posted March 18, 2008 I think the main issue is that all cars boost differently once modified, so you need a means of trimming the boost (hence the RR). It also seems necessary to adjust the exhaust restriction between Winter and Summer conditions as the boost differential is quite large. If only the wastegate was bigger on the J-specs.... 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.