The gearbox is very weak.I,m putting a modena box in it for next season.
The GTiR motor is an SR but has a lot better head and stronger con rods etc.My GTiR is a Dakar and ran 12.7 as a standard car with a good exhaust and a totally stuffed turbo that didn't last the first pass so it only went 20ks faster from 1/2 track to the end.
Jim richards Dakar ran 12.45.