As hard as it may be to believe, the 8% hp increase was from changing to a much richer oil mixture ( from 40:1 to 20:1) and then jetting accordingly for the richer oil ratio. We always tune our race engines with TRICK or VP Race fuels, and very rarely does fuel ever increase HP. The increase was purely based on the oil ratio change. More compression from improved ring seal, better lubrication top and bottom end. I wouldn't have believed it either, but it really made a significant hp increase. With a Banshee running so hard on top, it should prove to be good engine protection as well.