I have a small trunk that will only fit a box for 1 ported 12" or 2 sealed 12's. I've decided on 1 12". And I want a BTL and the specs on their site don't show up for the BTL's. I just want to know if these are good subs in the 12" size. I heard a long time ago when they had the old designs that there was bad tinsel slap with the 12's and that the 12's are hard to get to play low because they are spl subs and the fs is very high. So my questions are, Are they good daily subs? And also what is the "P chamfer" option, "Induct heat ring", and what does "Universal" mean?