[Lees68GMC]

The main thing I don't like about long tube headers besides the cost is their only advantage in flow performance is seen above 6000 RPM typically and every one made the collectors hang down below the frame rails.

Having done many hot rods and my 2nd GMC truck I wanted the entire exhaust up inside the frame rails. New Camaro owners love installing long tube headers on their New car, so the LS3 OEM exhaust manifolds are every where used and Cheap. Mine came off a crate engine never used. The OEM 5.3 truck manifolds hit the frame rails on these old trucks, these 2013 Camaro LS3 manifolds tuck inside the frame rails, you use the stock Camaro head pipes cut-off in front of the cats, preserving the O2 sensor bungs. My exhaust is run where I want it, No clearance issues. The LS3 Camaro made in stock configuration 436 HP with these manifolds. I'm happy, just my two cents