I have the 2x10" Upfire Zenclosures box and I have my amp mounted on the rear facing side of the box. Absolutely no problems what-so-ever. Love the look of all of it, and I'm often complimented on the setup. I don't have any pics right now as the grilles are being painted to match the theme of the car, but when I do they'll be uploaded.
I don't see any problem mounting the amp on the box so long as its firmly mounted..??
