does 2004 Mustang cobra need retune for smaller pulley

needless to say im not gonna get that car. dealer wasnt willing to work with me. i asked him to atleast get it dyno checked to see if the ecm was atleast tuned for the smaller pulley............anyways im still looking for 03-04 cobra.....next question is about the infamous engine tick on the cobra. is there a safe mileage for the cobra to have to say if the tick was gonna occur it would have done so by such and such miles. say for instance if no tick after 20,000 miles then safe to say it wont happen.......what was the precentage that 03-04 cobras had this issue. 2 out of 10 for example.......