Oh hey. First of all, the razors, such as the MX500/650 motorcycles, etc.., are all quite Currie-like. If you can do it to a Currie, you can be optimistic about doing it to a Razor.
If you add the battery to the Pocket Mod., you have an interesting problem. A not too powerful motor is now trying to spin faster. So while the results are pretty good taking the bigger motor on the MX and adding 12v, you're pushing it to a greater extent with the little, less than half as powerful as the MX motor you find in the Pocket.
I have not yet gotten around to yanking the controller from one of my MX to try on one of my Pockets. I'll bet it's perfectly compatible. http://shop.razor.com/MX500-MX650_Control_Module/ I'll also bet the motors are interchangeable. And I think the Currie scooter motors should fit, but all things I still haven't played with yet.
If you look on YouTube there's this kid that has experiments with adding battery to the MX with a plug adapter he sells himself. He uses a pair of 3.7v lithium batteries from his RC toys as the add on. http://www.yorbin.com/index.php?route=product/product&path=61&product_id=554
Haven't rode mine downtown, but I see adults doing it. Not sure how stock some are, others obviously are not. How fast would you say this little girl gets going? If you do get up over 20mph, what are you going to do for brakes?
[youtube]AlZkc60gp54[/youtube]
[youtube]d9Ev3kiHR5Y[/youtube]