What 13.5 are you using as 4.0 FDR sounds very low , ran 13.5 for the first time the other week with the 2.1 version and novak ballistic buggy 13.5 on 2nd notch of + timing on the can and profile 5 geared at 6.0 FDR and was only half a car lenth slower than tekin powered cars down the main straight at Bedworth.