One place offers these little gadgets that look quite interesting to me. They are electric fans that run directly off the battery when set off by a nos style switch in the throttle body. One of these units gives 1 PSI and a claimed 4-6% increase in hp. You can get a dual unit (two inline) for 1.7 PSI and 6-9% increase in hp. I have been thinking of putting one of these on my '85 mazda 626. I feel no need to try it on my already turbocharged Porsche. Here is their website:
http://www.electricsupercharger.com/www-electricsupercharger-com/autoprod.htm
Keith
79 930
85 626 (mazda)