The AFR's are excellent, expensive, and pre ported. The TFS Street heads, flow very well, are cheap, and unported. The GT40X I have yet to see make outstanding numbers on any car.
Sky
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-1989 Saleen Mustang #406- TFS Heads, E-303, edelbrock intake,70MM TB, 73mm MAF, off road H, headers and 3chamber flows.
12.55@107mph
Going for 11's on 87 octane with A/C and 20+MPG!!!