I've been using a foxpro inferno for a few years. I'm happy with it. It looks like the prowler is a newer and updated version of what I have. One think i've noticed when comparing to a friend's Icotec nightstalker, my inferno isn't quite as loud or crisp at high volumes. But many times full volume isn't needed. I have a foxpro SP-60 external speaker for my inferno. I rarely use it. The SP-60 seems to boost the sound a little, but not much.
I added some custom sounds to mine from MFK, tony tebbe, and predator tactics university. It looks like you can add sounds to the prowler too.
