Slayer Posted July 30, 2020 Share Posted July 30, 2020 Hello all, I have a 1995 UK spec supra, everything is stock except the exhaust. I believe it has a full 3” custom Exhaust, and I have a couple of issues with it. First, it is a bit too loud for my liking and does not suit the car in my opinion given everything else is stock... Secondly, I am having difficulties passing the MOT emission test. Could I have your opinion on what I could do please? Would any Jspec exhaust - 1st cat, 2nd cat and Cat back (including muffler and exhaust pipe) fit the UK spec supra? What about any combination of UK/Jspec exhaust component - for example, would I be able to fit a Jspec 2nd cat to UK spec 1st cat and cat back? Any advice would be most appreciated. Thanks. Quote Link to comment Share on other sites More sharing options...
Guigsy Posted July 30, 2020 Share Posted July 30, 2020 from memory uk spec cats are different bolt patern? (3 rather than 2?) i could be wrong though. the previous owner of mine gave me the cats with the car. and i kept them and gave them awa with the car too when i sold it because they are a bit difficult to get hold of. your other option is to find somewhere friendly who will let the emissions slide... Quote Link to comment Share on other sites More sharing options...
Scooter Posted July 30, 2020 Share Posted July 30, 2020 From the 2nd cat back you are definitely ok to use a stock J spec exhaust on a UK or vice versa. cats are different will hunt for specifics Quote Link to comment Share on other sites More sharing options...
Burna Posted July 30, 2020 Share Posted July 30, 2020 You will need both a 1st and 2nd UK spec cats, as they are both different to the J-specs. Then you will need a cat back exhaust. But be aware although it will be quieter, you will loose power. Currently you will be running around 1 bar of boost pressure with no cats in, as the larger UK wastegate will keep it at that. If you re-fit both cats, you will be back down to stock boost pressure of 0.7 bar. Quote Link to comment Share on other sites More sharing options...
Burna Posted July 30, 2020 Share Posted July 30, 2020 From the 2nd cat back you are definitely ok to use a stock J spec exhaust on a UK or vice versa. cats are different will hunt for specifics Differences are 3 bolt pattern on the first cat as Guigsy rightfully said, and the second O2 sensor in the second cat. Quote Link to comment Share on other sites More sharing options...
Scooter Posted July 30, 2020 Share Posted July 30, 2020 Try and see if you custom system has sections. Burna has pointed out the second O2 sensor the uk's which yours must I think still have. See if that section is separate, I don't think it's likely you have one whole piece? Depending on what you currently have will affect what you need! Quote Link to comment Share on other sites More sharing options...
Slayer Posted July 30, 2020 Author Share Posted July 30, 2020 Try and see if you custom system has sections. Burna has pointed out the second O2 sensor the uk's which yours must I think still have. See if that section is separate, I don't think it's likely you have one whole piece? Depending on what you currently have will affect what you need! Thanks very much for all the information guys, this really helps, much appreciated. I understand the drop in power by replacing the custom exhaust with OEM components. As you have correctly pointed out, the custom exhaust is made up of different sections, would I have any issue running the UK spec 1st cat and the UK spec cat back exhaust without the 2nd UK spec cat? Thanks for the advice! Quote Link to comment Share on other sites More sharing options...
Burna Posted July 30, 2020 Share Posted July 30, 2020 Thanks very much for all the information guys, this really helps, much appreciated. I understand the drop in power by replacing the custom exhaust with OEM components. As you have correctly pointed out, the custom exhaust is made up of different sections, would I have any issue running the UK spec 1st cat and the UK spec cat back exhaust without the 2nd UK spec cat? Thanks for the advice! Yeah that would do it, if you speak to Tim at TB Developments he sells de-cat pipes, and will be able to supply a 2nd UK spec de-cat to take the O2 sensor Quote Link to comment Share on other sites More sharing options...
Dnk Posted July 30, 2020 Share Posted July 30, 2020 If your car doesn't have either of the cats fitted it should fail regardless of the emissions Quote Link to comment Share on other sites More sharing options...
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