Slingshot Interior & Speakers Thoughts

I am about to redo the cockpit interior of my dated 1998 Slingshot. I have the colors narrowed down but I have a few questions for my fellow Hustler brothers out there. What changes or additions would you make if you were updating your cockpit interior? PPI-Innonvation will be doing the work. I am thinking about adding either velcro seat belts or hand straps for the rear passengers sitting in the 3 man bolster. no rear bench seat.

Also has anyone added or moved their cockpit speaker? Where are the speakers located, what size are they and what brand did you use? I am looking at JL M7.70 anyone have any inout on these speakers?

I'll start a thread documenting my progress once I start the interior tear down. Thanx-Rich