German company Manhart Racing has given the Z4 a huge power boost, taking the power output to a beastly 550hp. To attain this power, they gave the Z4 a new powerplant, the 5.0-liter V10 from the BMW M5. The gigantic V10 engine produces 550hp, and can take the Z4 from zero to sixty in just 3.4 seconds.
To handle the beast and remain stable, the Manhart Z4 M uses tuned Bilstein B16 PSS10 coilovers to rein in the power of the V10. It has a kerb weight of 1450kg, with a weight to power ratio of 2.6kg per hp.
Via: BMW Blog