RE: How can I hop up my F-27 stryker without going brushless?
To tell you the truth, the stock power system is pretty much maxxed out. There's only one way to get more power from what you've got, and that's to draw more Amps with a hotter motor or bigger prop. Problem with that is, the battery and ESC can't handle the additional load... In essence, a simple cheap motor hop-up would turn into a complete system overhaul anyway, with a new battery, and heavier-duty ESC.
The best way to hop up the F-27 without having to change everything out is a brushless motor and ESC. Because the brushless motor is more efficient, it puts more of the power to the propeller.
...and brushless really isn't that expensive anymore, especially compared to the complete system overhaul you'd have to perform just to run a bigger brushed motor on the F-27...