I'm fairly new to the E60 5 series, but I was reading up on the 550i which has 360 horsepower. There's a big gap in price between the 550 and the M5, so if an owner wanted to squeeze 400 flywheel horsepower out of the V8, how hard would it be? Would you have to go FI? Does anyone even make parts for them? :help

anyone? I know most of you will say E39 M5, but I really like the styling on the E60's but would like to know if they have any tuning potential

Dinan made 621HP out of a 400hp E39 M5. Supercharger and tuning will get you there.

I'm sure you can do similar with a 550. Tuning software might be hardest to find. Hell you prob dont even need a SC but maybe just some engine software and exhaust revamp might do it.

http://www.dinancars.com/Series.asp?Series=15&Chassis=13&Model=57&Class=Engine%20Tuning#1548

search around for tuner companies, Dinan, Kelleners, etc.

the most cost effective way would be to trade the 550i in for an E39 M5.

:guitarist the most cost effective way would be to trade the 550i in for an E39 M5.