Pre Cat Removal

Ruskie · June 10, 2004

Is this worth doing in terms of gains? Is it a big job? Will it still pass the mot? Does it affect insurance?

Questions, questions :duh:

TonyGoose · June 10, 2004

I've got no pre-cats and got through the first mot this week.

Fast Idle test.

RPM = 2770 (allowed 2500 -> 3000)

CO% = 0.004 (allowed up to 0.3)

HC ppm = 0 (allowed up to 200)

Lambda = 1.001 (allowed 0.97 -> 1.03)

Natural Idle test.

RPM = 658 (allowed 450 -> 1500)

CO% = 0.005 (allowed up to 0.5)

Apparently a 'test drive' to warm the remaining cat was required though :)

petejenkin · June 11, 2004

Not bad figures there Tony,

I think I will defo get mine removed. do you get much more power gain?

I bet she sounds nicer aswell

Zee007 · June 11, 2004

Tony (Like me, Gus, Duncan, Dave, Bazza etc) has a supercharger, and therefore the pre-cat removal is reccomended to avoid them breaking up and blocking the manifold.

For a N/A car, I suspect removal will only offer negligable gains....

petejenkin · June 11, 2004

Thanks for that Zee, but then again, any gain is a positive don't you agree?

It all falls in with the master plan anyway.........charger

Monster-Mat · June 11, 2004

Just to correct Zee, it doesnt block the manifold, it blocks the Main Cat

DUNCAN · June 11, 2004

I had my pre cats removed a couple of weeks before fitting my S/C.

Driving it round for those 2 weeks i noticed that the engine rev'd more freely which gave a sense of more power. It also made the zorst note sound deeper.