I built a friend´s nissan sentra with a single 3515 and a SS 4K, no clipping or anything of course, i told him to go slow on the first couple of days , he went to a party that night and used the car as the main atraction, next day, blown coil!!! Ordered the recone, install it again, a year after he´s pounding hard as hell and it´s one of the best 139.9 competitors con Panama right now; Anyways, after his experience, i never let the owner to play the system before me, i just use a 25 hz tone with a moderated volume for about 20 or 30 minutes and it´s good to go!!