I think you are confused. Apart from the $13K supercharger, Dinan does not really have mods that significantly 'juice up' the 540 in terms of power. Sure, one could probably squeeze out another 20-30HP, but it will cost you almost $4K to do it. My theory is that a lot of the mods have a placebo effect where they feel fast because the cost a lot, as surely they must be waaaaay better than those stupid engineers at BMW could come up with. But...If you have around $16K burning a hole in your pocket, then Dinan or RD can set you up with about 400HP...