here is the skinny from someone who has successfully used spray since 1977, in fact been building dedicated sprays systems for myself and others since 1980.
1) only use a fogger and or a dry system on a RACE ONLY CAR, they r far too temporamental and hard to dial in to b used on a street driven application.
2) the horror stories u hear and see about spray use are the same ones used to b so common with blower and or turbo charger use, and for the same reasons, inept use and or substandard parts.
3) if u plan to use more than 50bhp of spray, especially on an otherwise stock engine, its a good bet to invest in an automatic retard system since the general rule of thumb is that u employ 2 degrees of retard for every 100bhp used, thus u need at least 1 degree by the time u get to 50bhp
4) jus as foggers and dry units are best left to pro race drivers and crews, so to are progressive controller systems, for predominantly street use with a closed exhaust, best u stick with a wet plate. progressive engagers play havoc on solenoids, and even if u have a fuel pressure safty shut off u can still fry an engine right quick if ur fuel solenoid fails and the nitrous one still operates. wet sytems employ what is known as a fuel enrichment side, IE: they introduce additional fuel supply when the Nitrous is activated, dry systems do not.
5) if ur a novice, as in new user, don't listen to ANYONE other than the supplier of ur nitrous system and follow their instructions and recommendations to the letter. If u do, u'll enjoy many passes with blissful spay use, n the 1st time u make a full clean pass with spray, ur gonna b hooked so get ready.