A friend of mine and myself have a couple of O/T cars that we race against each other for fun. His is a '65 Chevelle four door wagon with a stock 283 with a two barrel, single exhaust and 3.08 gears with a Factory Muncie 4 speed. It has 90,000 miles on it. Mine is a '67 Falcon 4 door wagon with a stock 289 with a two barrel, single exhaust and 3.00 gears with a C-4 tranny. It has 81,000 miles on it. I usually pull him off the line bad, but he comes on strong in the mid range and beats me by a car length of two. Our rules are that the engines have to be stock appearing and sounding, but any other mods are ok. We check the strokes of the engines, so a bigger stroke is out of the question. I want to port the intake manifold, heads and exhaust manifolds to free up a few ponies. How much of a HP difference will porting everything make? Changing cams is also illegal.