3.5 inch/4 inch stock exhaust

[TRoberts]

Is there anything to gain on a stock 03 non HO engine by changing fom the 3. 5 pipe from eng to muffler to the 4 incher? [and new muffler]And am I thinking correctly that a later model elbow will fit and allow a 4 inch down pipe to be attached to my turbo? Thanks for any input.

 

[MR.K]

4" down pipe.....

Yea. . an 04. 5-06 down pipe (4") will fit if you change the cast iron elbow from the 4. 5-06 then change the the muffler to a 4" in & out then cut 4" off the tail pipe behind the old muffler to where it goes to 4". As far as performance ,if you are all stock, maybe a different air filter ,the yield is only 4-6 HP and about 60 Deg. reduction in EGT's . . the problem is the Hy 35 turbo with it's tiny 9cm housing is = to 1. 3" pipe opening... . so even a 7" exhaust really won't make any diff. untill you change the turbo... . I'm going to do this change (go to all 4") and add a phat shaft 62-14 with a 2 piece ATS manifold... THEN the new exhaust will do something when you add a chip... ... .....