When I replaced my Fiat 500 Abarth exhaust with a high flow coil and 2.5" exhaust system, it turned out to be VERY noisy. I mean, how noisy do you expect a race car to hit the track on a trailer, but I need an everyday car, and although the police don't issue loud muffler coupons where I live, the noise gets everyone on me I'm looking at a car, and since I also like speed a bit, I'll soon attract the attention of some law enforcement officer. So I cut 18 inches off my center tube and welded in this resonator. This made the noise just slightly louder than factory levels, louder than you might expect. From the factory, the Fiat 500 Abarth has no muffler or resonator at all. Overall, this direct resonator is efficient but not limiting.