Those cheap 'dry' kits are only really good for a bit of fun or a party trick. Dont buy off ebay tho, save yourself some $$ go to a bike shop and buy a co2 tyre inflator, get some fittings and set it up yourself. Then just buy some of the nos bulbs off ebay. The nos will come out a bit fast (too much of it and it gets wasted) just using this method, you need to try and regulate the flow by using a bump stop behind the trigger or being careful when you press the trigger.
As sed before there not really worth if your after performance, better off spending your money on some port work and tuning your engine. The nos hit from these bulbs isnt really enough to fry the engine, you get 20s max from one bulb, by the time you load up a new one the engine will have cooled and the temperature in the head become more stable. If your after a party trik go for it, ill probably end up fitting something similar for a bit of a laugh aswell as some engine work for blowing away my mates.