has anybody used the walker 50500 h-pipe?i think it is a 2 cat replacement pipe.is it 2 1/2 or 2 1/4 and did it help any?i think it is cheaper than the bbk or mac pipes,i need to replace mine but i need to replace my maf to match my injectors and my clutch is going,going almost gone and i'm not going to skimp on a clutch(centerforce and new frrp flywheel)so i'm going to have to skimp on the exhaust alittle.any suggestions appreciated.