Aftermarket headunit will most likely solve your problem. The 80prs seems to be the popular one. Change your HU and then try the SFB again. If it still isn't strong enough for you, or, your electrical can't push it, then, upgrade your electrical or get a Smart3.Would an aftermarket head unit still require a signal processor?
He needs more power the battery is not enough big 3, H.O. alt I suggest. That's what these guys told me to do. Especially with the SUNDOWN full bridge or the taramps you need your voltage on point. I'm only running 2200w rms and i had to upgrade all my electrical to get the most out of mineIt won't. People don't listen. People are stupid