What are you doing exactly with your system? Are you looking to do SPL or SQL? Or do you want an overall clean sound?

Friend who works with me had a W7, but was extremely dirty compared to the alpine. Anything over a 10 starts to become dirty depending on the music you listen to. Match the sub to your preference, not what you friend has.

 

All I can say is the that the 13w7 is one badass sub. A buddy of mine has one w7 with a 1000/1 amp in his jetta. He is hitting 140db with just one sub.

 

I have a 18'' Kicker Comp VR and its pretty good. But I would definitly go with JL Audio all the way they have the best quality and the most bang for the buck. Sure you might think that what u pay is a lot of money but hey its the best company so its worth it. My friend has a 13'' W7 in his car and its crystal clear and the bass blows my kicker out of the water. Dont listen to anyone that says that this and that is better the JL Audio line is by far better then the other brands!!!!

 

I have a set of Comps and I love it, yeah JL is so clear.