I'm a first time K5 owner and I need to know the necessary changes needed on headers for a 1988 K5 Blazer. It has the T.B.I. 350 with A/C. Also, I noticed fittings with metal tubing coming out of the each of the exhaust manifolds. What is this? And how do I accomodate those fittings for standard small-block Chevy headers?