[Gunnar]

I know. The Protege weighs 1,230KG, the Mazda3 is 1,530 I guess... That makes 300KG (600lbs?) for 40 more horsepower to the wheels.

And my Protege had only the muffler yes, but I don't think that the muffler will give any "real" gain in that type of Vehicle (except LOUD sound gain).

Lets assume that you are right, and that the muffler gives you no extra power. But then I bet that it is lighter than the stock one, thus less weight, and thus an advantage :wink: