Guys,

Here in the UK a cat is not required by law on my car. The only requirement is that the CO is below 4.5%. When I come to change the exhaust is it worth removing it? What sort of BHP increase would it produce? Is it easy to gut a cat or should I just make a new bit of pipe up instead?

Thanks

Simon Holtby

'88 Camaro 5.7 TPI

 

I was reading an artical the other day (In car Craft I think) that was testing cats. They did gain HP by removing the cat, but lost torque. But the total change was only 2-3 either way.

 

If it doesn't give more than 30 bhp I think I'll do my bit for the environment and leave it on!

Regards

Simon Holtby

88' Camaro 5.7 TPI

 

If your worried about pressure then leave the cat on and not use a muffler.

 

I've removed my cat and I've definitely noticed improved performance and better sound.


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If you remove the cat and end up with CO levels above 4.5%, try this. Overdrive the AIR pump! Get a pulley about half the size of the original and put it on before you go to the inspection station. That overdriven air pump will flush so much fresh air into the exhaust that it ought to help you pass your emissions test. Now, how much power will be lost I haven't any idea. But it's easier to change pulleys than to change out cat converters.