I recently got some hsk 165 as my front stage and Im running them off a ppi 900.4 and I love em and I very happy with my front stage. The only issue is my substage which consists of 2 sa8's v1.5 in a custom enclosure sound great with rap but lack the kick drum I would like from a sub setup. So what can I do? Maybe switch over to a single 10 like an sd-2 10 or try a different 8 inch drive. This is all in an f150 under the bench seat I'm a forward firing enclosure. Thanks in advance.