I will say one thing about bandpasses- a 500 dollar one will sound just like a 100 dollar one.
Only box I've ever heard that had standing waves in an open Jeep Wrangler. The box seemed like it was at war with the 2 Punch 10 speakers in it. If they ain't big, they suck- way to peaky at some frequencies, absolutely hideous at others and somewhere in between, there isn't any bass at all.
The JL Audio Stealthbox in my Cabrio is what I would expect of a quality piece, and for the amount of craftsmanship, attention to detail, US made and legendary JL Audio performance. It's worth it's price.