The new 2009 Z4 Roadster leaves some people wanting more. They already miss the M Coupe and Roadster. Manhart has taken this fact to heart and dropped the V10 found in the M5 and M6 into the Z4.

The huge 5.0-liter V10 engine develops 542 horsepower (compared to the stock 343 hp figure), which is also 42 horsepower more than the M5 makes thanks to a new AC Schnitzer exhaust, HJS racing cats and a reconfigured ECU. Manhart mated the engine to the original M5 E60 6-speed manual and differential, while Fichtel & Sachs provided the clutch.

Acceleration to 60 mph is claimed to take just 3.9 seconds, and top speed is slated at 208 mph. Final curb weight comes in at just 3,212 pounds, meaning it has a power-to-weight ratio of 5.93 pounds per horsepower – better than the Ferrari F430's 6.5 pounds per horsepower figure.

Bilstein B16 PSS10 coilovers were installed to give it a more aggressive stance, and Manhart finishes off the package with 19-inch blacked-out BBS Challenge rims wrapped in 235/35ZR front and 285/30ZR rear tires.

You can get your hands on this V10 creature for the equivalent of just over $137,000.