I currently top out at 70, although 65 is comfortable. As soon as an incline comes along down she goes! Offroad its fairly good but i do find a few situations where the engine is too gutless until its on boost, it will rev too 3500 quite happily. I fitted Methanol injection 50/50 mix of methanol and water, which improved it greatly but only comes in after 8psi of boost. Its the Jap designed perkins. The engine never came turbocharged and so is retrofitted with a turbo, the engine is 80hp N/A. The main problem is that the fuel pump hasnt been changed so it doesnt increase the fueling when on boost, i think this is the main downfall.
A chip from twisted will increase the bmw 30hp and increase the torque by 60nm, JE also do a chip that produces similar results.