not bad... its infinitys lower level sub..... so you're not gonna get mind blowing bass from it... but they are tight and relatively loud. A big plus, they use a small box... .75 cubic feet sealed... so even 2 of them wont take up much space. (My boston box is almost 2 cubic feet for 2 - 10's, and I barely notice its there!)
Throw them about 300 watts RMS a piece for a pair... or 500 RMS for a single and you should get some pretty good, solid bass from them. I did a pair a while back with only 150 RMS watts a piece, and they still hit pretty well.
I say go for it.