I really like the idea of this. The price might seem hefty at first glance, but such a 'box has its benefits.
In a simple sense, it's plug & play. Take your old box out, chuck the Passon in - drive away.
The biggest factor is no cutting/welding - but it goes beyond that. Firstly, whist we'd all like to think we're handy with the tools, truth be told, most of us don't have either the skill-set or space (or both) to pull off such a job, which means it has to farmed out, which = $$$$$.
OK, so 99.97659% of us don't have uber-rare #'s matching Hemi's, but chopping into a average car still has it's dilemmas. You still have to strip part of the interior (front carpet, console & seats), to do the job - that takes time, and in the hands of a professional, time costs money. Then what? Do you just patch it up, chuck some primer over it, and leave it as is? Plenty of folks would do just that, but think of all those that just had a full body re-spray - I don't care what kind of car you have, not having to cut up something you just spent a butt-load of time & money on is a bonus & a half.
By this time, that initial extra $ of the Passon is starting to look pretty damn good - so long as their quality, warranty & customer service are on point - I'd say it's definitely worth a look at.