Guy's,
I use these electric brakes:
http://www.rcgroups.com/forums/showthread.php?t=2261620
I have a set on 90mm 10lb L-39 and they work great. I definitely need them as our asphalt strip is a little short for jets. The quality of the machining and the quality of the rubber tire are excellent and the price is very reasonable. JP Hobby in China is one of the trusted manufacture's out there. The owner (Shane) keeps a presence in the forums and is there to help out. They also sell electric retracts and some very nice all metal EDF units. I am waiting for them to release the larger version of the brake units as I need a 4" set for my Panther.
Dean