My Sons Xray was set with a 4.9 fdr, prior to using the boosted software. After I put the boosted software into the esc the car was slower with around 48 degrees of total boost and turbo timing.
I changed the pinion from a 29 down to a 24 giving a 5.95 fdr and it was heaps faster. The other thing maybe your battery but I would try ratios first.
Dan