My thoughts exactly. You will be disappointed stepping to one 10" from 2x12", it's like a swap for V6

 

As for your coating question... yes, 3M ruberized undercoating works very well go sound-deadeing; I've got 12 cans inside my car... I've used it on many many cars and it works wonderful.

one word of advise though... mask of EVERYTHING you don't want it on... once it hits, it's pretty much bonded on...

 

I agree. Every time somebody thinks they can get the sound of two 12s out of a single 10 stealth, all they want to do is gripe because it's not loud enough. Like duh. Btw, the dual box only weighs 30 lbs empty. You won't find a lighter dual box anywhere. I'm pretty sure your subs combined are heavier than the box. Maybe if you went with some lighter subs it would help. Or maybe you could try this. Get a stealth for everyday driving and just drop in the 12s when you go to a show or whatever. I have two or three different setups I can put in my car at any one time.