Discussion
Hello Mark
There are two sets of cats basically, the pre cats and the the main one in the fat section of the "Y" pipe (commonly called the dustbin!).
The pre cats are there (someone else correct me if this is wrong) for cold idling emissions and type approval. They can be removed and should gain 5+ bhp.
Since there would then be less "stuff" in the exhaust it will help the underbonnet temps. I have a 500 and there is so much more heat under mine than a friends precat 400.
If the main cat is left in then the car will be fine for the MOT as long as its not stone cold
.
There are two sets of cats basically, the pre cats and the the main one in the fat section of the "Y" pipe (commonly called the dustbin!).
The pre cats are there (someone else correct me if this is wrong) for cold idling emissions and type approval. They can be removed and should gain 5+ bhp.
Since there would then be less "stuff" in the exhaust it will help the underbonnet temps. I have a 500 and there is so much more heat under mine than a friends precat 400.
If the main cat is left in then the car will be fine for the MOT as long as its not stone cold
.Second above.
1. Small performance gain, but large if pre-cats have disintegrated and are not flowing... Exhaust note changes but not excessive.
2. Legal, passes emissions test - just have a good blat first so main cat is nice & hot before test.
Try searching "precat removal" there is plenty of content on PH.
Dave
1. Small performance gain, but large if pre-cats have disintegrated and are not flowing... Exhaust note changes but not excessive.
2. Legal, passes emissions test - just have a good blat first so main cat is nice & hot before test.
Try searching "precat removal" there is plenty of content on PH.
Dave
Hi Fella,
I removed my cats about 6 months back to fix the common 'shunting at low revs' problem and it worked a treat! and to answer your questions:
1. I didnt really notice any performance gain, but there was a noise increase (now its the same db as my mates 4.3BV)!! and it sounds nicer!!
2.IT wont pass the MOT and yes I believe it is illegal. It will pass the MOT by just putting back in the CAT Y piece.
You will have to change the tune resistor to a green one, so it runs a richer fuel map for without cats (to get the full benefit) and then change it back to the white one for MOT time so it knows about the llamdas.
IF you do it, I would also recommend doing the engine mounts at the same time and obviously new manifold gaskets and I went for SS bolts aswell!
Got the Non cat Y piece from Tim at ACT.
Sadly I am selling my Griff and there is a piccie of the engine bay with the nice shiny non cat Y piece here... www.pistonheads.co.uk/sales/115262.htm
Overall worth doing but will be costly, for me it was either this or a MA chip, this route was cheaper and IMHO better.
Lig.
I removed my cats about 6 months back to fix the common 'shunting at low revs' problem and it worked a treat! and to answer your questions:
1. I didnt really notice any performance gain, but there was a noise increase (now its the same db as my mates 4.3BV)!! and it sounds nicer!!
2.IT wont pass the MOT and yes I believe it is illegal. It will pass the MOT by just putting back in the CAT Y piece.
You will have to change the tune resistor to a green one, so it runs a richer fuel map for without cats (to get the full benefit) and then change it back to the white one for MOT time so it knows about the llamdas.
IF you do it, I would also recommend doing the engine mounts at the same time and obviously new manifold gaskets and I went for SS bolts aswell!
Got the Non cat Y piece from Tim at ACT.
Sadly I am selling my Griff and there is a piccie of the engine bay with the nice shiny non cat Y piece here... www.pistonheads.co.uk/sales/115262.htm
Overall worth doing but will be costly, for me it was either this or a MA chip, this route was cheaper and IMHO better.
Lig.
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