I'm confident on Mechanicals, and that's what I'm buying. Gas mileage means nothing to me. I didn't build this truck for MPG's, it's strictly fun and adrenaline. What I don't like about my VS Carter AFB-same as an Edelbrock, is that it doesn't perform off the line, and is just okay through the rest of the power band. When I 've run mechanicals on two other cars in the past, a nearly stock 350 on a 63 Impala, and a very mild 327 on a 62 pickup, when you punched it you could actually feel the power and sound when the 4 barrels were open, and on mine you can't really feel the power, and the sound. It almost seems like a decent 2-barrel. Oh well, thanks, and the mechanicals it will be. If i have problems, I'll sell the TH400Turbo, and convert it to 4 speed, or tremec. It's actually something I've thought about.