Try running 50 shore tyres in the rear, then run 30 shore tyres in the front to compensate for the hard rears. Forget 40k oils inthe diffs, what you need is a spool front and rear. Also, light purple springs are no good, hot pink is more your colour. Change the gearbox as well, get one of those trick gearboxes with reverse gear, then you will be able to drive in reverse, you will probably finish more races as you won't be snapping the front suspension arms as often. Don't worry if you can't go quite as fast in reverse, because you will still give Grub a flogging.