[djseed]

I have a 501 in the SPF and .68 overdrive in the T5. For me, any gear numerically lower than 3.73 would make it terrible on the highway. If you build a radical engine (high lift mechanical cam, high compression and single plane manifold) you will not be able to use 5th gear unless you are doing 80 or 90 mph. You can always scream around in 4th but that seems like mechanical cruelty. In town you can pick your poison - 2nd to 4th. My engine thumps along at 1500 to 2000 on the highway. I have a mild hydraulic roller cam, 9.9 to 1 compression and a dual plane manifold.