thats odd, what other mods have you got? mines been totally fine since fitting, but my only mods are panel filter, hks ssqv and the spec 2. although in 3rd and 4th gear, some times the revs jump up and then drop, like i was dipping the clutch slightly for a split second, im thinking its either slipping clutch or boost spike (the boost lights jump to 3 when the revs jump then drop back to 2 when it goes back down)