ive had a worn cam twice in the space of months that was piper tho the symptons i had was the first time the car wouldnt rev past 5k after that it would miss fire, the followers were getting stuck. and the second time there was a slight miss fire at idle and was getting that tappy way, im now back to the standard cam and feel its the best the cars went boost seems to be a lot stronger and a better drive hope this helps