Is it true that no cat gives your car better gas mileage. Has anyone heard an E36 without one. Will the sound be too loud?

should give you better gas mileage. exhaust will flow better.

JOEY

The main restriction in the exhaust system is the muffler. Removing the catalytic converter probably won't increase either the sound or the fuel mileage.

Was true in the 70's, with the horrible designs of early cats. Not worth the trouble now.

reduces scavenging if removed

It sounds kinda raspy with the OEM cat hollowed out.

Your best bet would be a test pipe along with O2 simulator so your car doesn't throw any check codes.

Great mod for increased horsepower and engine response.

I didnt notice any better gas mileage when I had mine removed it that matters to you. Mine is a daily driver and I get about 19-20 MPG's mostly highway

Just don't get caught with your cat removed. Hefty fines where I live.

i have no res's or no cats on mine with a dinan exhaust sounds fine (very little rasp) but havent noticed any gas mileage improvement