I ran type R's for a long time. you have to have a box built for them. a pre-fab will sound like poo... I ran mine in a 1.25ft3 with a 2inX23.75in vent. I had an alpine MRD-500 running to each. I hit 152.3 in my jeep liberty. so they can get loud, but they will blow if you arnt carefull...

when trying to compair subs, you should compair the type X to a W6... you will be blown away by the sound quality out of the X. I run W6's in my mustang. they are louder, but wont touch teh frequencys the X will. it drops way way lower. 10hz to 200hz is no problem for the X, the W6's stop around 12hz. and drop off after 155hz. both are great subs, and are about equal in power ratings. the X's sensitivity is a smidge better though.

It is hard to compair to a W7 though. that sub is a monster. If paired with Zapco or JL amp, it will blow most other single sub setups away. ( dont put more than 1000watts to a W7 if the enclosure is ported... They bottom out and blow. I have seen it on many customer cars.)