advice after tune
so my buddy took his 2000 ws6 to the tuner yesterday in which we are good frinds with. he has slp lid, ms3 cam 237/242 .603/.609 112lsa,1 3\4 lt's, 3" ory, ported ls1 manifold, comp dual valve, springs, lunati push rods and stock heads with a 3 angle valve job. High flow cats as well. Now he put down 400 whp and 406 tq. Now the car does not have a muffler right now it just runs through the headers, y and high flow cats and is dumped over axles. the tuner said if we added a catback with a chambered muffler it will really help. With no muffler he has no back pressure and by adding the cam he said he really needs that back pressure. He then also said to see a big jump do the F.A.S.T intake and bigger maf sensor. We all know that will add power he was just making suggestions. What I really want to know is it really worth it to spend the money on a catback if it will make that much difference or not.

