Im running a methanol kit on my daily driver (
www.alkycontrol.com). Its not straight meth.....more like washer fluid which is about 40% alky. The car has a M90 roots blower which gets hot as hell. W/out the alky I was only able to run 13* of WOT timing on the 3" pulley....with alky I could run 19* of WOT timing on the 3". Alky works, but only use as much as you need to quench the detonation. I used too much at first and hydrolocked my 1st motor sending an exhaust valve through the block but that's a story for another day.
Nitrous is a whole other animal. The kits instal the same as an alky kit but nitrous is for making mad power and torque. It does have a substantial cooling effect but that's not its main purpose..power is. Alky won't get you 1 more HP unless you turn up the timing...which is why most people run it. Alky is a cheap alternative to 105 octane race fuel.