Besides Dinan, I have looked into Powerchips, Jet Chips and Conforti however Conforti does not make one for the 540. Has anyone tried Jet Chips on their BMW's they offer a money back quarantee and the software cost only around $250 give or take the Power Chip is $200 more.

Thanks!

There is also Upsolute but few have tried them.

Never heard of them? Have a web addy for info? Thanks

www.upsolute.com They claim 300+ hp. I forget the actual figure but you can look it up.