How do the Axis 15" stack up to the 15" BTL in terms of SPL running off a SAZ-3000? I never heard any of Audiopulse or any TC Sounds products I'm just curious and I know the BTL beats pretty hard.

The BTL is a much more efficient driver. It is also geared more twards SPL.

The AudioPulse is an SQ sub first...output is a bonus

Aight cool. I dont mean to be a pain and ask too many questions but i'm doing research on some subs I might look into buying in the near future. Right now I'm looking at 2 15" BL's or so. So wat about 15" Death Penalty Series and how do they compare to the BL's performance wise such as SPL and SQ? I know the BL's are geared toward more Spl but I heard they sound pretty good too.