IMO, I would do the following:

[link=http://shop.boomtownhobbies.com/main.sc]Boomtown Hobbies[/link] carbon fiber tailboom and flex skids.
The tailboom will reduce weight and the effects of rotor wash. The skids are stronger.
You will definately notice an improvement in maneuverability and handling with the tailboom. I strongly suggest a CF tailboom upgrade.

Also, a shorter and/or lighter flybar greatly increases maneuverability and control. A search can find threads on this and everything else listed. A flybar mod is a must after gaining some experience.

Venting the 4 in 1 and canopy reduces heat.

I'm not a big fan of aluminum parts unless you break the same part over and over; adds weight.

Light kits are pretty cool, although I don't have them.

Keep reading and searching there's a lot more that can be done.
Good luck.