removing the cat

[Cypher007]

can i remove the cat from my exhaust system or is it gona send the lambda sensor nuts. i plan to fit a straight piece of pipe in place of the cat and leave the original back box on. i did wonder if it was possible to run in the same diameter pipe from the front pipe to the backbox and from the backbox to the rear, thus taking out the restrictive smaller sections of pipe or will i loose to much back pressure and screw up the engine management system as my friend sugests?

[Peter Milnes]

Only if your car need not have a cat by law. I forget the date from which all new cars had to have a cat.

All the best, Peter.

[Simon Linton]

As Peter says if you remove the cat from a late model car, it will no longer pass its MOT and be legally unroadworthy and thus uninsured.

Driving without insurance is a criminal offence and you're likely to lose your licence.

There are "performance cats" which retain the legality and do not restrict the flow of gases unduly.

I would strongly suggest you follow that route otherwise you'll be in a bus for a very long time.

[Mav_UK]

Personally I would get a professional road sports exhaust. If you remove too much back pressure then you will lose performance - it's a fine balance and probably best left to people who do it for a living. On the whole, I would say that if you do this, but leave the original back box you'll probably not get any extra power anyway, and sports exhausts sound fantastic (not talking cheery bombs here, but proper full exhaust systems!)
Stu

[Dan F]

Hi.
MAV UK is correct in his back pressure statement, as your car is N/A, it needs a degree of back pressure to operate correctly. (different with turbos where as little back pressure as possible is benefical, as you will never remove the turbine from the exhaust stream and therefore will never completely eliminate back pressure from a turbo engine.....)
I digress however....

As your car is a 1992, you can quite happily remove your cat.
It was from May 1993 that cats became mandatory.
Your lambda sensor shouldn't do a thing unless it is attached directly to the cat. If it is in the down pipe as mine is on my T4 then it shouldn't be affected. The lambda sensor is there to ensure correct fuel to air ratio, this just happens to prolong the life of the cat as well. I would get it replaced with a silencer rather than a straight piece of pipe however, as this will give only slightly less back pressure and probably add about 10hp as well.

Please be aware of course all of this is done at your own risk, however legally you should be OK.
I have had 2 440s that had cats that I had removed, as they were stifling the performance of the cars. Both were 1991 cars.

Cheers,
Dan.

[noiseboy]

I have the sports cat from Don Norchi and it rocks!!

The cat adds several BHP, but more importantly a lot of low end torque cos the turbo spins up better. The pipe is wider and the cat itself is a high-flow design.

I would really recommend this as a way to go.

Regards,

Phil :-)

[davebslater(uk)]

i thought 92 was the cutoff year , anyway remove the cat - as long as the lambda sensor is there everything will operate fine

[Cypher007]

thank you for all the info, i think ill take it off and see what happens, and yes you are correct Dave it was August 1992, fortunately my car was registered in April 1992 ;)