My friend has a 99 Galant, with Motzart muffler on it. (I've never heard of it). The thing has the deepest tone I've ever heard. He says I shouldn't get one, cause it's for a 4 banger, and it would decrease my performance. Is that true? Would it really be that bad to put one one? And if it is, why don't I put duals on, and have 2 Motzarts. Would that be good for my performace?