did you strip anything out between the swaps? or is this just the diff between a stock 350 weight vs stock 455 weight? I did not strip anything out of the car. It was just a engine swap. I thought there would be a bigger difference. If I remember correctly, both times were just below a half tank of gas also. I did come in over 4000 pounds once with my 350. But then I did remove things out of my interior. example; Horseshoes, In cabinet speakers ..... But I think there was 3/4 of gas in the tank.