The front will lift under hard launching,thats why you need to get the front as low as poss so that you dont get too much movement in the front suspension... obviously the more weight you have in the back,the more your engine has to pull,the slower you will go.4x4 was correct,you need the damping on fairly hard,and harder poundage springs will reduce squating.Reducing air out of the tyres will preduce fast times and improve grip no matter what tyres they are!!!!
This sort of suspension setup WILL drive like a bag of shit on the roads,understeer etc,BUT NOT in a straight line,which is what you asked about in the first place mate