I have been shopping around looking at buying some headers for me 03 Silverado 5.3 and really would like to know the stock manifold inlet size before I spend a lot on headers.
I see headers come in 1.1/2 and 1.5/8 inlet sizes and would like to know if changing to either of these would give much of a gain in air flow?
I already have 2.1/2 from the manifolds back tru duals and next I am planing turbos or supercharger so if anyone knows of good ones of either of those let me know plz.
(I don't want to spend a lot on them but if i need to then I will.)