Looking to find 40HP? Hmmm. I remember back in the 80s Hot Rod dragstrip tuned a 383 Chevelle at LACR. They picked up a full 1/2 second in the quarter mile, by careful tuning. For me personally I bought my dad's old sand-rail and was able to go from losing to him in the drags to beating him in a drag race up a sand dune simply by re-jetting the 48 IDA webers and upgrading the ignition system. So I know that a lot of HP can be found by careful tuning.