Slant Six 170 vs. 225

When we were racing my wife's '73 Duster, the 2 1/2" exhaust pipe was the most significant upgrade. The second was a TransGo shift kit in the transmission. The SuperSix and the Autolite 2100 was a distant third. Upgrading to a Offenhauser manifold with the same carb didn't make any difference in elapsed times.