You might try Superchips at www.superchips.co.uk. They claim an increase of 45 bhp, and 97 nm of torque. List price is 600 pounds. They actually only list chips for the E53, but the engines are essentially the same. Several friends here have chipped their E53's and are quite happy. I plan to do the same to my E70 when it comes in a couple of months. The only down side for you may be that they are pommies