ordered the Turbo Catalytic Bypass Tubes for my 04CTT
02-09-2011, 01:37 PM
#2
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You ;might want to get (if you dont have already) a half moon, closed end 13 MM wrench for the hard to get bolt you will find.
02-09-2011, 04:22 PM
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You will get a much better performance gain by replacing or gutting the primary cats. Then just put the secondary cats back on the the mot.
The 1st cats really limit ignition advance and flow.
When I get mine (struggling to find a good one) the 1st thing I will do is Gut the 1st cats and put on 2nd cat bypass pipes. that is an easy 20bhp.
The 1st cats really limit ignition advance and flow.
When I get mine (struggling to find a good one) the 1st thing I will do is Gut the 1st cats and put on 2nd cat bypass pipes. that is an easy 20bhp.
02-09-2011, 06:30 PM
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You will get a much better performance gain by replacing or gutting the primary cats. Then just put the secondary cats back on the the mot.
The 1st cats really limit ignition advance and flow.
When I get mine (struggling to find a good one) the 1st thing I will do is Gut the 1st cats and put on 2nd cat bypass pipes. that is an easy 20bhp.
The 1st cats really limit ignition advance and flow.
When I get mine (struggling to find a good one) the 1st thing I will do is Gut the 1st cats and put on 2nd cat bypass pipes. that is an easy 20bhp.
These pipes should be good for 25 to 27 HP
02-10-2011, 04:29 PM
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The 1st are really the 2nd
Working from turbo back. the 1st cat WILL be the most restrictive. Gasses are hotest so have the greatest volume. The bigger the pipe and the better the flow will help power. As the gasses travel through the exhaust the gasses cool and the gas volume reduces.
The cat bypass pipes you will buy will be the 2nd Cat after the turbo where the gasses are cooler so less volume to pass thought the 2nd cat.
I did loads of testing on my Audi 2.7 twin turbo re the above and found by gutting the 1st cat i could run more ignition advance with no det. The 2nd cat had little or no effect and i could not run anymore ignition advance when the Cats was removed or in place removing both I could run more advance and saw a big improvement in power.
I will Gut the 1st cat ( cel will need looking at ) and use bypass pipes for the 2nd cat. Re-fit the 2nd cat for MOT time.
Working from turbo back. the 1st cat WILL be the most restrictive. Gasses are hotest so have the greatest volume. The bigger the pipe and the better the flow will help power. As the gasses travel through the exhaust the gasses cool and the gas volume reduces.
The cat bypass pipes you will buy will be the 2nd Cat after the turbo where the gasses are cooler so less volume to pass thought the 2nd cat.
I did loads of testing on my Audi 2.7 twin turbo re the above and found by gutting the 1st cat i could run more ignition advance with no det. The 2nd cat had little or no effect and i could not run anymore ignition advance when the Cats was removed or in place removing both I could run more advance and saw a big improvement in power.
I will Gut the 1st cat ( cel will need looking at ) and use bypass pipes for the 2nd cat. Re-fit the 2nd cat for MOT time.
02-10-2011, 05:14 PM
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Here you go. 1st in line are primary. 2nd are secondary.
http://www.6speedonline.com/forums/c...es-review.html
http://leistungmotorsports.com/porsc.../2ndary-bypass
Links should help.
Sorry for link to different forum, hope that is ok
http://www.6speedonline.com/forums/c...es-review.html
http://leistungmotorsports.com/porsc.../2ndary-bypass
Links should help.
Sorry for link to different forum, hope that is ok
02-10-2011, 06:26 PM
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The 1st are really the 2nd
Working from turbo back. the 1st cat WILL be the most restrictive. Gasses are hotest so have the greatest volume. The bigger the pipe and the better the flow will help power. As the gasses travel through the exhaust the gasses cool and the gas volume reduces.
The cat bypass pipes you will buy will be the 2nd Cat after the turbo where the gasses are cooler so less volume to pass thought the 2nd cat.
I did loads of testing on my Audi 2.7 twin turbo re the above and found by gutting the 1st cat i could run more ignition advance with no det. The 2nd cat had little or no effect and i could not run anymore ignition advance when the Cats was removed or in place removing both I could run more advance and saw a big improvement in power.
I will Gut the 1st cat ( cel will need looking at ) and use bypass pipes for the 2nd cat. Re-fit the 2nd cat for MOT time.
Working from turbo back. the 1st cat WILL be the most restrictive. Gasses are hotest so have the greatest volume. The bigger the pipe and the better the flow will help power. As the gasses travel through the exhaust the gasses cool and the gas volume reduces.
The cat bypass pipes you will buy will be the 2nd Cat after the turbo where the gasses are cooler so less volume to pass thought the 2nd cat.
I did loads of testing on my Audi 2.7 twin turbo re the above and found by gutting the 1st cat i could run more ignition advance with no det. The 2nd cat had little or no effect and i could not run anymore ignition advance when the Cats was removed or in place removing both I could run more advance and saw a big improvement in power.
I will Gut the 1st cat ( cel will need looking at ) and use bypass pipes for the 2nd cat. Re-fit the 2nd cat for MOT time.
The first are secondary...
We talk about the same stuff and I am taking the same ones out
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02-10-2011, 07:25 PM
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02-10-2011, 07:58 PM
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I dont believe anyone. I do all my own work. Most folks have no idea ( not meaning you) once i find a CTT i will post all my findings much like my BM
www.bmw535d.co.uk
cool car, sold now though. Goes on Saturday
www.bmw535d.co.uk
cool car, sold now though. Goes on Saturday
02-11-2011, 10:07 PM
#12
Moderator !x4
OK enough
There are 4 cats on the cayenne
The first are in front of the O2 sensors, so if you gut them most likely in the US you will fail emissions, the second are behind the O2 sensors and are for sound control.
There are 4 cats on the cayenne
The first are in front of the O2 sensors, so if you gut them most likely in the US you will fail emissions, the second are behind the O2 sensors and are for sound control.
02-12-2011, 02:06 AM
#13
resonators and mufflers are for sound control. Cats are for emissions. Cats are too pricey for a manufacturer to use as a sound/noise control device. Yes, they may mute the DB but that would not be their primary role.....
Cheers
Cheers
02-12-2011, 05:39 AM
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I live in the the UK so emissions will be fine.
02-12-2011, 07:13 AM
#15
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