I'm running it in my 340 (1970 340, in my 72 Challenger) and love it. I have 10.5:1 compression, slightly worked over X heads, Edelbrock performer rpm intake (1776), Edelbrock 750 carb with an electric choke (1411), Doug's ceramic coated headers (D453), 2000 stall in a 727 with 3.23 gears out back, and the car runs like a champ. My brother who has a 73 Challenger with a 440 is afraid to race me with. I haven't had it at the track yet or on a dyno, but the car really moves. I really want to install my 3.91's and see what it can really do, but there goes my highway speeds and I have a tendancy to go on 250 mile trips. Oh and on the freeway right now I am getting better than 16 mpg at 70 mph. I'm sure with some more tuning I can get the fuel economy even higher.