The S63TU is very underrated and quite often gets the same horsepower to the wheels that we get at the crank. The S63 and S63TU are not nearly as similar as people may think. Do a search on
www.realoem.com, very few parts are cross compatible between the X5M's S63 and M5's S63TU...at best we share a similar engine architecture and an ///M badge on the trunk.