i know of some1 local to me who runs 5mm spacers on the front running 18" bbs lm reps and he has had no trouble, i used to run 19" rs6's on my mk4 with 5mm spacers but i used some 5mm extended bolts as the rs6s where some heafty mo fo's, choice is yours but personaly id get some extended bolts to match your spacers for piece of mind,like you said its playing on your mind!