right now i have 2 12s in a sealed mdf box and they hit pretty hard. but ive been looking at a fiberglass box but its only a mono chamber. would this make the sq lower? also would you reccomend inverting them or just filling the box with alot of polyfil?

 

You don't state is your current box dual chambers ???
You have to look at the specs of the subs for airspace required then check that against the fiberglass box you are looking at ...
Inverting the sub raises the amount of airspace as you don't have the magnet ect inside the box, you do have to reverse the polarity of the wiring ...
Polyfill is a way to fool the sub into thinking it's in a bigger box, but won't make up for large differences

 

oh sorry. yea my current box is dual chambers. and i just checked and the fiberglass does match the specs

 

Next comes to power you are running and quality of the fiberglass

 

im pushin 1000 watts. but as far as quality. im not sure. im hoping pretty good

 

Some of the cheaper prefab boxes flex pretty good with 500 watts over that they can start cracking ... I've had to reinforce some of them to prevent this