Do I need two small cats?

[C4PNE]

I am not talking about the furry kind!

I need to replace the exhaust manifolds on my Chimaera 4L.

One option is the standard S/S JP manifolds without the two small cats that are on the standard manifolds.

Has anyone experience of these?

Will they pass an MOT?

Will they make the car sound different - better (louder ) or worse (quieter )??

Any help would be great.

Regards, Paul.

[David Beer]

You will pass the mot if the car is up to temperature, the main cat doing its job. Sound, some say there is a drone at 2500 rpm, not bothered me and i have a "super sports exhaust" from ACT.

[C4PNE]

David Beer said:

You will pass the mot if the car is up to temperature, the main cat doing its job. Sound, some say there is a drone at 2500 rpm, not bothered me and i have a "super sports exhaust" from ACT.

Does the super sports exhaust include the manifold or is it the section after?

ACT gave me a price of £542 for their standard stainless manifolds ex cats. How does this compare with the price for the super sports and would they offer any advantage over their standard units?

Does it pass the MOT comfortably or just scrape through?

Thanks, Paul.

[David Beer]

Forums are funny old things, is anybody else seeing this thread ? I have standard manifolds, minus cats( hammered out!) then the act exhaust. At mot time its always below any spec.

[spend]

The pre-cats (in the manifolds) don't make much difference - they are only their to aid when everything is cold. Once up to temp the main cat is sufficient for most all of us, but we are being thrown a bender cos the car is a Ginetta in Scandinavia, with questions being asked about a wilder cam.

I have not heard of anyone having any undue problems with Emissions after changing cams - only when they have tried to pass with both pre-cats & main cat removed. This is however a very big YMMV area..... (oo I can become PM now )

DAve