With substantially greater torque and bhp from our Roadster's we (John V6 and I) also suffered tyre to roller slip given the cars unusually low weight c. 950Kg. We did consider afterwards that extra weight in the form of passenger ballast would have helped. Revival's solution at the time was to squirt almost continuously in Morton's case, WD40 onto the tyres. Holding the car down was another issue which took a little longer on my car with 5 link rear. Worth noting that the dyno will (or should) report slip though hence several calibration runs on each of our cars. A GDI engined Plus 4 was seen on a later dyno session and on a cooler day to need only one calibration run as no slip issues.
