Their are lots of upgrades you can do with a hummingbird. Here is what I've done to mine
Main motor-This was the first thing on my Hummer to wear out and the brushless will last along time and provide more power(stock motor about 3 ½ s of flight time
(I used the Astro 010 w/ CC Phoenix 10)
Head Stiffener- This was essential to do Forward flight(reduced conning effect which cause severe pitch up Lipoly Battery- increased flight times to almost 15 min. (Etech 1200mah 7.4v)
Separate Speed Controllers-stock mixer operated at low frequency making tail motors not last as long. More importantly separates was MUCH more precise by being able tune the tail to a more solid tail rotor with revolution mixing
MS CF Blades-increased head speed dramatically creating a much more stable heli in wind and Fast Forward Flight
Ball in Swash-Increased control by giving the swash more movement(small silicon tube was replaced from Main shaft)
Shaft Collar- this was inserted to hold up the main rotor assembly and cause less friction(the silicon tube also did this)
{Pictures can be found here: http://www.runryder.com/gallery/07713/}
Cheers
tomflier