Anyone ever buy an under the seat powered subwoofer?

Im looking to add a little bit of base to my mini gp. It came with the basic basic radio and the low is just horrible. Ive been looking at some under the seat powered woofers because i do not want to take up any space.

Was wondering if anyone has one and what brand it is.

thanks!

I was looking at the Sound Ordnance B-8PTD on Crutchfield. They said the MTX basstube sounded much better so I got it. The tube sounds ok at low volume and bottoms out with any amount of volume. I would definitely get some first hand experience before buying but I wouldn’t expect much.