STI Decat (Bugeye)
06 December 2007, 11:08 AM
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STI Decat (Bugeye)
Hi All,
Quick Q, If i removed the centre cat on my 52 STI Type UK, would I have any issues?
I am not planning on touching the cat in the down pipe...
I already have a H&S cat back system but have a Centre decat pipe in the loft not doing much!
Would it make any difference?
Cheers
Quick Q, If i removed the centre cat on my 52 STI Type UK, would I have any issues?
I am not planning on touching the cat in the down pipe...
I already have a H&S cat back system but have a Centre decat pipe in the loft not doing much!
Would it make any difference?
Cheers
06 December 2007, 12:55 PM
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The downpipe cat is the more restrictive of the two, so you will only get a small improvement, you'll get a bit more of the burble due to loosing the silencing effect of the cat, and you'll be a little less legal than you already are....
Simon
Simon
10 December 2007, 10:24 PM
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Think the check engine light is only an issue with the WRX, not STI.
Are you saying you have a H&S backbox and centre pipe fitted or the standard centre pipe and the H&S backbox and are planning on swapping this for the decat centre ? By centre pipe I mean the piece that connects from the sprung joint to the backbox, not the short piece where the lambda sensor is located. I'm not sure if your year of car would have this pipe or a single piece downpipe like a classic.
If you remove just the centre pipe and leave the main cat then you will probably be fine and totally legal and pass an mot no problem. If you remove all the cats then your car will probably overboost in higher gears and cause a surging effect under acceleration as the ecu adjusts things to try and bring it back to target. I have an 01 jdm sti and had this problem with a full decat exhaust. It requires adjustment to maps, changing of the restrictor or use of some other sort of boost controller to resolve.
Hope this helps.
Are you saying you have a H&S backbox and centre pipe fitted or the standard centre pipe and the H&S backbox and are planning on swapping this for the decat centre ? By centre pipe I mean the piece that connects from the sprung joint to the backbox, not the short piece where the lambda sensor is located. I'm not sure if your year of car would have this pipe or a single piece downpipe like a classic.
If you remove just the centre pipe and leave the main cat then you will probably be fine and totally legal and pass an mot no problem. If you remove all the cats then your car will probably overboost in higher gears and cause a surging effect under acceleration as the ecu adjusts things to try and bring it back to target. I have an 01 jdm sti and had this problem with a full decat exhaust. It requires adjustment to maps, changing of the restrictor or use of some other sort of boost controller to resolve.
Hope this helps.
11 December 2007, 08:58 AM
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Think the check engine light is only an issue with the WRX, not STI.
Are you saying you have a H&S backbox and centre pipe fitted or the standard centre pipe and the H&S backbox and are planning on swapping this for the decat centre ? By centre pipe I mean the piece that connects from the sprung joint to the backbox, not the short piece where the lambda sensor is located. I'm not sure if your year of car would have this pipe or a single piece downpipe like a classic.
If you remove just the centre pipe and leave the main cat then you will probably be fine and totally legal and pass an mot no problem. If you remove all the cats then your car will probably overboost in higher gears and cause a surging effect under acceleration as the ecu adjusts things to try and bring it back to target. I have an 01 jdm sti and had this problem with a full decat exhaust. It requires adjustment to maps, changing of the restrictor or use of some other sort of boost controller to resolve.
Hope this helps.
Are you saying you have a H&S backbox and centre pipe fitted or the standard centre pipe and the H&S backbox and are planning on swapping this for the decat centre ? By centre pipe I mean the piece that connects from the sprung joint to the backbox, not the short piece where the lambda sensor is located. I'm not sure if your year of car would have this pipe or a single piece downpipe like a classic.
If you remove just the centre pipe and leave the main cat then you will probably be fine and totally legal and pass an mot no problem. If you remove all the cats then your car will probably overboost in higher gears and cause a surging effect under acceleration as the ecu adjusts things to try and bring it back to target. I have an 01 jdm sti and had this problem with a full decat exhaust. It requires adjustment to maps, changing of the restrictor or use of some other sort of boost controller to resolve.
Hope this helps.
Hi Ken,
Thanks for your reply. I have an H&S backbox, centre de-resonated section and currently ALL cats in place. The pipe I have in the loft is of my old 51 WRX from a few years ago and is a short de-cat pipe to remove the centre cat pipe (the on that joins the downpipe and the centre de-resonated section)
This would leave the downpipe cat in tact and to my knowledge the STI does not have a cat in the up pipe. This would leave one cat in place for MOT time and still keep the car legal?
Cheers
Iain
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