Decay possibilities.

[mike ryan]

I have got an allroad with a bau engine fitted. I have it booked in to be chipped. I was wondering if there was any value in decating it prior to this. Will it make any difference to the performance? Will it have an effect on anything else? If I do it can I just remove the cat internals from the existing exhaust leaving the old cat externals in place, or is it better to take out the whole thing and put a straight pipe in its place? If it's removed will it make the exhaust louder?

any help or experiences of this are welcome.

[MarkTM]

Mike, yes it will give you a few more BHP and will be louder if replaced with a straight pipe.

You may however fall foul of the new MOT regs that state if it's supplied as standard then it must be there.

Failing that replace with a sports cat or a new cheapy one which will both be less restrictive than your current one.

I had the cats (there are 2) on my V8 jag, the difference is it runs on LPG so as a result is at least 5 times less polluting than a petrol version, I also have a sports exhaust so that it sounds like a 'proper V8'. No problems for me at MOT time.

[mike ryan]

Mine is a diesel so emissions is not a factor. If i do remove them I am sure that they will still pass an mot, as the mot tester can't have intimate knowledge of how every car looks. Besides if I could remove the internals they would not be any the wiser.