pre cats

[daz the plumber]

can any one tell me where the pre cats are in the manifold and are they easaly removed .ive been told if the pre cats are removed only it does not make any difference for the mot .

[spend]

They are in the big bit just before the y-piece where the lambda sensors are, and after the 4 headers join. They only affect warm up for MOT, just give the car a good blast before the MOT and you should dee no difference.

Dave

[daz the plumber]

to remove the pre cats can it be done with out taking the manifolds off as its a big job .will there be any advantages by removing the pre cats only .ive been told the exhaust note is better and the manifold os a little cooler . will there be any tuning needed thanks daren

[That Daddy]

No retuning neccesary,yes the manifolds run cooler in that area,cant comment on doing them in situ(i done mine when i changed maniflod gaskets)it does not upset the MOT emissions in any way,there is a noticable drop in under bonnet temps

[daz the plumber]

how are they removed , is there any cutting and welding

[spend]

Big Chisel & bigger hammer

Dave

[GreenV8S]

If they're blocked you may get small power gains and a slight noise increase - or rather, recovering the power that they were costing you. If they aren't blocked the only gains are likely to be in your head. If you've already got the manifolds off for other reasons and the chisel is burning a hole in your pocket there's no particular reason NOT to do it, but TBH it's not the sort of thing I'd do just for the sake of it.

[RumbleBee]

If they look to be in flawless condition, I wouldnt bother taking them out. Mine were, and it took 4 solid hours of banging, drilling and levering, not to mention grubbing around in the toxic dust. If they are damaged, then there would be more point and it should be much easier.

[Zippee]

GreenV8S said:

If they're blocked you may get small power gains and a slight noise increase - or rather, recovering the power that they were costing you. If they aren't blocked the only gains are likely to be in your head. If you've already got the manifolds off for other reasons and the chisel is burning a hole in your pocket there's no particular reason NOT to do it, but TBH it's not the sort of thing I'd do just for the sake of it.

What he says!!!
I had to have my manifolds replaced as they were cracked and I went for ACT de-cat stainless manifolds mainly because they were cheaper than the OEM replacements.
However, there is IMHO absolutely no difference in sound and as already stated unless your cats are blocked it'll make no difference to the car.