Ive changed my 5 1/4 to 6 1/2, added hogtune 6×9 lids, ( all speakers r JL Audio C2s) and im running a soundstream pn4520 (I think is the model num). Im running the stock head unit (2011) and I think the system sounds pretty good, but I would like better. My question is, does an aftermarket head make an noticeable difference compared to the stock? Do u hav a suggestion on a unit if it does? Thanx in advance!