i am making my custom sub box and right now i am not sure if i am going to have 2 15in subs or 2 12in subs in the car yet. i heard that 12 are the best for 3 gen. but i have 2 15in subs on a shelf so i was going to go for the 15s but they are made by two different compunys so i would have to get another but if 12s are the best i was going to do that instead. one is a 15in volfenhag and the other 15 in sub is an audio pipe. i also heard that volfenhag is really good. i have made a template of the box first http://www.cardomain.com/ride/3090728/5
so my ? is what is best for the type of box i am going to have and i am planing on making it a sealed box no vents/ports

 

well it all depends on what you want to use the subs for if you want good sound quality go with the 12's they give you a good low beat. now it you just want to shake the living hell outa your 3rd gen then go with the 15's. 15's are what we car competition subs if you your gunna go for db's they hit HARD.