I use the alkycontrol kit (
WWW.ALKYCONTROL.COM)
Good kit, developer has a lot hands on experience with different vhicles / conditions. Have a look at the alky/nitrous subforum at
TurboBuick.Com - The World Wide Web under BOOST! - Buick Grand National, GNX, T-Type. The developer is very active there, and theres lots of positive reviews of that kit.