Exhaust system

[racid3th]

my vehicle [VX SS Commdore sedan, manual] is fitted with extractors ,pacemaker brand, the cats have been removed. does this cause to use more feul?

i have got a set of complete monaro HSV exhaust system off a VX and i was wondering if i put it on will it improve my feul economy since it has cats in it.

also, what modifications to my rear suspensions to make my car handle as good as later model VX?

thanks

[BowTieGQ]

It is highly illegal and irresponsible not to have cats installed. Believe it or not, they actually do work to lower emissions but don't hurt performace on even a strong engine. If you engine is putting out some serious power, than maybe get 2.5" or 3" cats. Otherwise save your money for better stuff like maybe trying to get more power first. When cats first came out, heaps did restrict the flow due to idiot owners putting leaded fuel in car and the lead causes the cat to collapse and stop gas flow. I'm not saying your irresponsible either. I don't know why the exhaust shop wouldn't refit them.

[VY03]

And the fine is pretty heavy as well if caught

[racid3th]

there is no restriction in NZ i dont think. im not worried about noise but feul efficiency.
i think you missunderstood my question. if i fit a standard set of HSV monaro's extractors or the whole system will it help my fuel economy? im not after a noisy vehicle. at the moment i have a single big bore system with no cats.