Lighter the better really, less then 1000kg, but I still want a Radical SR8 which has 363bhp and weighs 650kg. I know the engine can be tuned to at least 450bhp with just a boring kit to increase it from a 2.6L v8 to a 3.0L v8. Yes that would be nealy 700bhp per tonne, which i bet could be raised to 800bhp per tonne with some tuning.