hp went from a very conservative 325bhp, (realistically 337), to a true 360bhp. Not that big of a deal, but dig enough to change in price. There is no "Ci", it is just "i". The new 3-series coupe will not have a "ci" denotation either. Anyway.. 0-60 in 5.3 for the 4.8 and 5.5 for the 4.4-liter. Dinan has some parts for the 4.4i which are great. Intake, high-flow throttle body, and exhaust new 23 whp.
If you are looking to replace your M with a quicker BMW coupe, don't. The 6 is more luxury and is a BIG car, almost as long as a 745i.
2006 Corvette Z06 Red/black
2006 BMW M5 Sepang/Sepang SMG III
2006 BMW M6 White/Black 6-speed