Want to get rid of one of the cats from my classic MY99.
Which will give me the best performance increase, centre or front? Is it worth replacing just the front and maybe the backbox?
I understand the centre cat alone may not pass the MoT but I reckon if the front pipe is well lagged it is worth a try.

 

Ditch the front one,fit a decat down pipe.(centre cat should pass the mot)
OR fully decat the system and find a 'good' mot tester
OR refit the cats for the mot.

A full decat will give you the best power increase plus better turbo response/spool up.

Mine is fitted with the Haywood and Scott full system......perfect fit and sounds the bo**ox

steve

 

Removing the front cat will give the biggest gains.
Some people get lucky and pass the emisions test with just the rear cat.
If it fails it is because of the emisions, so lagging will not help.

Replacing the centre section and back box will improve performance and sound and it will still pass the mot.

Greg

 

Thanks for the comments.

I believe not passing emissions with only the centre cat may be partly due to it not heating up enough (they need to be really hot. So lagging the down pipe will help to reduce heat loss and warm up more quickly and may help with emissions if they don't leave it long enough.

And it will reduce noise in the cabin.