deanmr2 Posted September 12, 2021 Report Share Posted September 12, 2021 Hi all I have a 2002 Boxster S Tiptronic with a PSE and was wondering if anyone has ever fitted a second cat bypass pipe with the PSE ? I really like the sound of my car but was wondering if the bypass pipe would further enhance the sound by giving out some more decibels. How would this effect the emissions ? Would it throw a CEL ? Would it still pass an MOT ? Would be very interested to hear if anyone has done this mod and their thoughts on it Cheers Dean Quote Link to comment Share on other sites More sharing options...
Nobbie Posted September 12, 2021 Report Share Posted September 12, 2021 2002 Boxsters only have one cat on each bank unlike the 987, bypass this and it will never pass on emissions. Aftermarket SS manifolds improve the sound and replacing existing cats with ‘200 cell sports cats’ might help as well although these can be a bit iffy with emissions from memory. Quote Link to comment Share on other sites More sharing options...
map Posted September 12, 2021 Report Share Posted September 12, 2021 (edited) … My original text basically repeated the above. Edited September 12, 2021 by map Quote Link to comment Share on other sites More sharing options...
deanmr2 Posted September 12, 2021 Author Report Share Posted September 12, 2021 21 minutes ago, Nobbie said: 2002 Boxsters only have one cat on each bank unlike the 987, bypass this and it will never pass on emissions. Aftermarket SS manifolds improve the sound and replacing existing cats with ‘200 cell sports cats’ might help as well although these can be a bit iffy with emissions from memory. Hi Nobbie thanks for your reply my car definitely has two cats per bank could it be the 2.5’s and 2.7’s have one cat per bank and the 3.2’s have the two cats per bank not sure about that Quote Link to comment Share on other sites More sharing options...
GmanB Posted September 12, 2021 Report Share Posted September 12, 2021 I don't think a decat will work on the later models as I think they have o2 sensors pre and post cat. Not sure when that was changed. Quote Link to comment Share on other sites More sharing options...
deanmr2 Posted September 12, 2021 Author Report Share Posted September 12, 2021 18 minutes ago, GmanB said: I don't think a decat will work on the later models as I think they have o2 sensors pre and post cat. Not sure when that was changed. It loots like the decat pipes come with a tapped boss to screw the o2 sensors into Quote Link to comment Share on other sites More sharing options...
Nobbie Posted September 12, 2021 Report Share Posted September 12, 2021 1 hour ago, deanmr2 said: Hi Nobbie thanks for your reply my car definitely has two cats per bank could it be the 2.5’s and 2.7’s have one cat per bank and the 3.2’s have the two cats per bank not sure about that I’ve always thought they only got two cats per bank with the 987 where the first cat is part of the exhaust manifold. Not sure if this diagram will show correctly, but it is for a 2002 986S and shows only two cats in total, one each side. Not sure where the extra cat would go🤔 https://www.design911shop.com/pages/diagramsBrowser.aspx?categoryID=2&diagramID=3203 Quote Link to comment Share on other sites More sharing options...
deanmr2 Posted September 12, 2021 Author Report Share Posted September 12, 2021 38 minutes ago, Nobbie said: I’ve always thought they only got two cats per bank with the 987 where the first cat is part of the exhaust manifold. Not sure if this diagram will show correctly, but it is for a 2002 986S and shows only two cats in total, one each side. Not sure where the extra cat would go🤔 https://www.design911shop.com/pages/diagramsBrowser.aspx?categoryID=2&diagramID=3203 It is the same setup as the 987 with the first cat being integrated into the exhaust manifold and the second one just before the muffler as per design 911’s diagram Quote Link to comment Share on other sites More sharing options...
Nobbie Posted September 12, 2021 Report Share Posted September 12, 2021 50 minutes ago, deanmr2 said: It is the same setup as the 987 with the first cat being integrated into the exhaust manifold and the second one just before the muffler as per design 911’s diagram Doh, I didn’t look at the diagram I posted properly. I am an idiot🙄. You learn something new everyday. Quote Link to comment Share on other sites More sharing options...
deanmr2 Posted September 12, 2021 Author Report Share Posted September 12, 2021 15 minutes ago, Nobbie said: Doh, I didn’t look at the diagram I posted properly. I am an idiot🙄. You learn something new everyday. No sweat my wife reminds me what an idiot I am most days 😂😂 Quote Link to comment Share on other sites More sharing options...
edc Posted September 12, 2021 Report Share Posted September 12, 2021 I had a 2000 and currently 2004 S and one cat each side for both. Quote Link to comment Share on other sites More sharing options...
deanmr2 Posted September 13, 2021 Author Report Share Posted September 13, 2021 8 hours ago, edc said: I had a 2000 and currently 2004 S and one cat each side for both. Your car has two sets of cats. One set is integrated with the manifolds and the other is downstream by the muffler which are probably the ones you saw. The bypass pipes delete the 2nd set of cats by the muffler. Here is a pic of the stock system off the car next to fabspeeds pricey system. Use of the cat delete pipes yield about 5-8hp gain typically and a little more sound. http://i100.photobucket.com/albums/m2/Porsche_Daddy/Fab_vs_factory.jpg Quote Link to comment Share on other sites More sharing options...
deanmr2 Posted September 13, 2021 Author Report Share Posted September 13, 2021 3 minutes ago, deanmr2 said: Your car has two sets of cats. One set is integrated with the manifolds and the other is downstream by the muffler which are probably the ones you saw. The bypass pipes delete the 2nd set of cats by the muffler. Here is a pic of the stock system off the car next to fabspeeds pricey system. Use of the cat delete pipes yield about 5-8hp gain typically and a little more sound. http://i100.photobucket.com/albums/m2/Porsche_Daddy/Fab_vs_factory.jpg This post from 986Forum.com may have answered my original question Quote Link to comment Share on other sites More sharing options...
map Posted September 13, 2021 Report Share Posted September 13, 2021 My UK car (986s manual 2002 chassis) has one cat per bank. Just like @edc’s My car has never had a cat on/near the manifold. Three systems have been fitted to my car - Factory, CarGraphic and Bespoke. None of them have manifold cats. I can see what the diagram shows - is that for US spec cars I wonder? Or maybe even something for a Tip version 🤔 Quote Link to comment Share on other sites More sharing options...
deanmr2 Posted September 13, 2021 Author Report Share Posted September 13, 2021 22 minutes ago, map said: My UK car (986s manual 2002 chassis) has one cat per bank. Just like @edc’s My car has never had a cat on/near the manifold. Three systems have been fitted to my car - Factory, CarGraphic and Bespoke. None of them have manifold cats. I can see what the diagram shows - is that for US spec cars I wonder? Or maybe even something for a Tip version 🤔 This is getting stranger by the minute all I know is that my car has the exact exhaust setup to the standard exhaust diagram above ie two cats per bank with one integrated into the manifold. I wouldn’t think it would be any different on tip cars from manual cars, if you go onto Design 911 website and check out their exploded views of the 986 Boxster exhaust system it shows two cats per bank Quote Link to comment Share on other sites More sharing options...
edc Posted September 13, 2021 Report Share Posted September 13, 2021 I've had the manifolds off on both cars and no cats 986forum is US and they do have 2 sets. If you have the bulbous 987 style manifolds with cats then they are aftermarket. Various sellers sell these on eBay etc as fitting 986. Quote Link to comment Share on other sites More sharing options...
edc Posted September 13, 2021 Report Share Posted September 13, 2021 Fabspeed is also a US company so all their stuff is based on the 2 cat per bank US systems. Quote Link to comment Share on other sites More sharing options...
deanmr2 Posted September 13, 2021 Author Report Share Posted September 13, 2021 Thanks this might explain the confusion Quote Link to comment Share on other sites More sharing options...
map Posted September 13, 2021 Report Share Posted September 13, 2021 @deanmr2 - do you know if your car had a replacement engine? Quote Link to comment Share on other sites More sharing options...
deanmr2 Posted September 13, 2021 Author Report Share Posted September 13, 2021 Not as far as I know but I do know the PSE was retro fitted perhaps that’s got something to do with it Quote Link to comment Share on other sites More sharing options...
edc Posted September 13, 2021 Report Share Posted September 13, 2021 If you want to free up power and a little noise swap the standard rear cats for 200cell ones and sell on the cat manifolds. If budget is no problem go for one of the higher end sports manifolds that @map talks of or I have used on both my cars now the cheaper eBay version often now branded as Gravity or Toyosport. Quote Link to comment Share on other sites More sharing options...
deanmr2 Posted September 13, 2021 Author Report Share Posted September 13, 2021 Thanks edc will look into that maybe the sports cats are the way to go Quote Link to comment Share on other sites More sharing options...
deanmr2 Posted September 13, 2021 Author Report Share Posted September 13, 2021 56 minutes ago, edc said: If you want to free up power and a little noise swap the standard rear cats for 200cell ones and sell on the cat manifolds. If budget is no problem go for one of the higher end sports manifolds that @map talks of or I have used on both my cars now the cheaper eBay version often now branded as Gravity or Toyosport. Did you have any problem passing the MOT emissions with the 200 cell cats? Quote Link to comment Share on other sites More sharing options...
½cwt Posted September 13, 2021 Report Share Posted September 13, 2021 6 hours ago, deanmr2 said: This is getting stranger by the minute all I know is that my car has the exact exhaust setup to the standard exhaust diagram above ie two cats per bank with one integrated into the manifold. I wouldn’t think it would be any different on tip cars from manual cars, if you go onto Design 911 website and check out their exploded views of the 986 Boxster exhaust system it shows two cats per bank This is is also in the parts catalogue on the Porsche website (same drawing, 202-05), however is shows the 4 car system whereas ROW cars (for the UK and most of Europe as well as other less restrictive emissions environments) are 2 cats, one per bank and also 2 O2 sensors, one per bank with not cat in the manifold. The parts cat is rather misleading on this as it seems to be US market orientated. Quote Link to comment Share on other sites More sharing options...
deanmr2 Posted September 13, 2021 Author Report Share Posted September 13, 2021 Yes see what you mean I think Design911 just use Porsche’s catalogue for their website which does seem to be US market orientated Quote Link to comment Share on other sites More sharing options...
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