Progressive Nitrous systems....

I had great luck with the NOS mini. It's cheap, easy to program with the handheld remote (once you go through it a couple times), and can do a lot for it's inexpensive price. Pretty much anything someone with a single plate kit could want, even make a single kit mimic 2 stages (had fun playing with that). Plus, it doesn't suffer from emf issues as much as some of the more advanced controllers. Tried and true (though older) product that works.