I decided to get and Efan, I know that it doesn't work for everyone but I think it will for me. It is an LS1 fan out of a WS6 trans am with new motors. It uses the newer Flex-a-lite controller, and requires either a bypass or a custom tune to turn off the SES light. It was an easy install following the instructions on the TV forums. It all hooked right up using the ground by the battery on the fender wall, the positive post on the fuse box, and the ignition fuse in the fuse box via a fuse tap for an ignition signal. Additionally I spliced into the red wire on the AC compressor. It has worked well cooling my truck in the very hot (100+) temps we've been having here in St. Louis, for the past several weeks.
The Flex-a-lite controller allows for an override, fan off, and, fan on, switch to be connected. This is a flex-a-lite part which operates off the ground or negative side of the battery. More or less this means if you ground out the pin on the controller the fan will either turn on at 100% ( for overheating conditions) or turn the fan off (for water crossings, etc) Flex-a-lite sells a switch most likely for some god-awful amout, but I decided to use a DPDT (double pole-double throw) switch so I could have both functions, override on and off) with one switch and still have the auto functions of the controller as well. The way my DPDT switch works is it has on-off-on positions. It has a total of six connections but only three are required. I connected the ground to the middle screw, either side it's not important, and I connected the override on to the same side on the bottom screw and the override off to the same side on the top screw. When the switch is flipped up it connects the ground to the bottom wire and when it is flipped down it grounds out the top wire. When the switch is in the middle neither wire is grounded. This allows me to have override on, override off, and the auto function of the controller available from one switch. It works great and I would encourage anyone else who is interested to do a similar mod. The switch is sold at Radio shack for about 4 bucks and for the wire I used an old extension cord because it contains the 3 wires required for the switch.
I am going to make a better switch mount I just haven't figured out where my switch panel will be yet, and this is my first switchable thing I've installed.
Oh yeah I threw a pic of my Volant CAI in there for good measure