Ok, I might just try out the 15. I have actually never even used this sub before. I bought it from a friend for pretty cheap. It doesn't have a huge magnet or crazy travel or anything, but It should be easily upgradable. Last night at the comp, the highest two 15 inch spl was 142 from a Q logic 15 with my amp in a 4 cubic Ft ported box, and a 143.8 in a 2 cubic ft box. Are these numbers low? I am pretty new to SPL comps. The equipment these 2 were using were certainly not top of the notch.