Well I'm not a straight line expert but I know enough that adding weight is not the answer,the lighter the vehicle the faster the E.T.... Sounds to me like ya need to get the thing to transfer weight to the rear wheels on the launch, you don't tell us anything about your suspension set up, so heres some general guidlines, drag shocks on the front, raise the nose of the truck, ladder bars on the rear . softer rear springs, move ballast such as fuel tank,battery,etc. as far rearward as possible......hope some of this helps.