the higher your XO, and the shallower the Q, the more boomy it'll sound and the more vocals you'll get through the subs. you lose the deep tightness you get from a lower XO frequency. ideal is usually between 50-80Hz
can you clip or fry your amp if you put the crossover too much? or any other side effects?
Nah...but I dont see why youd even try. It sounds like crap if you have it crossed anything higher than 80Hz. If your stereo is missing "punch" you should invest in some good midbass speakers for rear fill, or up front in kicks or the doors. Dont use a subwoofer to compensate.
oh yeah i see what youre saying, now i have this question, do the subs sound better if i face them towards the front of the car or have them face away, they are in my trunk, i have a camry. dont know if that means anything.
Normally youll get a larger gain if you load them off the back of the car. so...facing away from you