I run a set of the original round-port HO Tri-Y headers on a '64 GTO bracket car. The car has a full 3" exhaust hooked up to the 2-1/2" collector, makes for great mid-range and pretty decent top-end power.
The engine is a fairly mild 455 with 8.6:1 compression, the '71 HO heads have some bowl work and very minor port clean-up. Runs the HC-03 cam (244/252,.550/.554" w/1.65s) and a stock Torker II/650 DP Holley.
Best ET (3550# race weight):
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Even with the small carb and 2-1/2" collector it wants to rev to 6K, but I shift it at 5200. You can make very good power with Tri-Y headers.
These headers cost $350 OVER 10 YEARS AGO.
The new version being offered by TUNNEL PORT is a must-have for 2nd-gen bird owners and they are priced right. Don't blow what very well might be your only chance to get your hands on a great set of headers.
