DD is actually incredible but pricey. I said Fi, cause I think you get great bang for the buck with them. Real high quality product, and does not cost an arm and a leg. But watch out, they do not seem to like to play over ~ 63hz. I mean they do, but I dont like the way they start to sound, I found the same with CSS SDX10's. Other than that, they sound amazing. But I do not mind the low freq, as my fronts are crossed at 60hz/12db, but not a lot of mids can play well with this set-up.

Then again, if anyone asks me to recommend sub/s, I do not give many options. I love Fi Audio, and Stereo Integrity. Install, speaker location, tuning/xover frequency are most important anyways.

 

Like alot of ppl have said already, DD, FI, RE, TF1, American Bass, AudioQue, MMATS, they will all perform well for ya, i recently switched from RE to TF1 and i couldnt be happier. It took me 1 box and a couple hours tuning to get louder than i got my RE. The RE treated me well but tended to blow up on me quite a bit. The TF1's in my opinion, if it matters, is the best subwoofer available in canada right now, and being that they are manufactured in the build house of one of the above named companies, they are very reliable, very strong, and very reasonably priced.

 

i agree TF1 is by far the best for the price.