I like a bit of an air flow getting to my Outrunners.
I use a 2.25 Great Planes E. spinner.
http://www3.towerhobbies.com/cgi-bin...?&I=LXRBB4&P=7
About $10
Weighs about 20 grams.
You have to ream it out to 8MM and do some shaving on the plastic but it's pretty easy.
I've found that the lighter the weight the motor has to rotate the better. That's a reason I think it's a benefit to run a good carbon fiber prop. In these cases I'm using Rasa but the PT props are just as good. The CF props have the benefit of saving at least an ounce over the comparable APC's. I also think that the props are a lot stiffer and better overall and worth the extra expense.
http://www.f3aunlimited.com/rasa.html
The lighter weight has less wear on the motor and bearing.
The reason for the spinner being smaller is for 2 reasons. First these super light weight spinners only come up to 2.25 inches. Second I want the cooling that the smaller spinner allows.
I've run nothing but the Dubro aluminum spinner hubs for the last few years but I think this has a much more appealing look.
Just wanted to share. Mike Mueller

Neat way to handle cooling. I've also seen these spinners with a bit of the tip cut off for airflow. Similar to a Feudenthaler for folders.
Walt

Mike, on my AXI 5330's the 8mm shaft is to long for the spinner hub to seat on the thrust washer. If you had this problem too; how did you shorten the shaft? Cutoff wheel, hack saw.... I don't have a 8mm die to chase the threads.

Hey Mike I don't recall having that problem. I might have but honestly can't remember. I guess if I had to cut it down I would put a nut on first then cut the shaft and when you take the nut off it should correct the threads. Mike