nowalls said:what about our poor environment then?
Often the exhaust is changed, some people decat, but most leave the cat.
There is some extra gain in repacing the cat.
The average cat's have a flow of 45-65% [400-600cfm types]
One can fit a sports cat with 100-200cfm flow 85%
I am working in the automotive industries for a very long time and have worked also in the environmental research. In all these years I have been involved with TVR, Lotus, Rover, Land Rover, Saab (when it was independent), Porsche, GM and Norton on some projects and had dealings with other manufacturers on another level. So far none has been in the position to provide any conclusive test that would allow to draw any conclusion in support of the use of cats for environmentally friendly reasons. If anyone institution ever comes up with one I am absolutely willing to eat humble pie, which is a longstanding offer of mine.
The cat has so far proven only advers effects. Other than a higherfuel consumption it does create cyanide, H2SO3 and sulphuric acid to name a few. What the cat achieves in theory, mother nature does in a much better way within four hours.
Cats are good business. But not for much longer. Rising fuel cost, increasing safety standards and increasing demands for accessories, which increase fuel consumption and therefore increasing costs again, will eventually lead to abandoning the cat, which slowly proves to be a curse for the manufacturers.
Fiat has got in the current vrange one model that passed homologation requirements without the use of a cat.