As Neilp says. Mine has similar ever since the Berks HFC & short ram intake were fitted. Not so much judder but say if your in fifth doing 60 & you plant the foot or coming out of bend in say third & accelerate then you get some kick back after a slight hesitation. It doesn't make the car undriveable but its definitely noticeable. Does your car feel slightly less smooth/more lumpy at idle? After speaking to Mark at Abbey he confirmed my symptoms to be common, especially on HR models & said a remap would sort it out. I'm just waiting to buy an exhaust & hopefully for Abbey to confirm a Scottish tuner for the Up rev to get it done.