I ran a Phoenix gold Titanium in one of these and it couldnt handle it. Whenever the sub hit the deeper notes the box would Flutter as if it couldnt handle the bass. Alright box i guess you just have to run a lower power sub. I had 550 RMS @ 4 ohms
These boxes are at their best with MTX subs (that's what they used to test them) duh! I'm running an old MTX 12" and it sounds great with a MTX251 200rms.
Put my Alpine 12" Type X" in this box and It made a huge difference.Sounded much cleaner and deeper.The box is pretty well made although it is not the best.They are not the same as their former sledge boxes that used 1"MDF but its pretty good. Im running two Alpine Type X's in these boxes powered by 1 RF 1500BDCP amp,Big 3,Yellow Top The whole nine yards in a Ford Rager Extra Cab4X4 .Subs was originally in the old universal 12" boxes.For me,it made a big difference.Couldnt give it a perfect score because of the price.
I had this box with 1 10 in 9500 @2ohm with an old school orion 1000 watt amp and it never blew in 2 years and was loud as sh*t one of the best setups I've ever had without any issues