Very nice! I just googled stealth subwoofer boxes for mazdaspeed 3 (after seeing this resurrection post) and your original install post came up in the search. Great job on the install, super clean!
Looks pretty good but if I can give a word of advice for next time, just tape around what you are dipping so you don't have to take parts off your car. Plastidip is very easy to remove during and after dipping. And if you get a little over spray just wipe it off with a clean terry cloth or micro...
How does that infinity sound? I just ran across those on amazon recently and they seem to have pretty good reviews. Is there a significant difference between that and the stock sub's that come in most cars these days? They look pretty beefy and infinity is a great name so I would imagine so.