I'd get the MSD SCI+. I'm running the exact setup I think you want to be. Right now, i'm running my ignition timing at a 2degree advance all the time, so therefore if I want to run a 55 shot, I set the ignition to retard 2 degrees so that it brings it back to 0 when running nitrous. right now I have the 65 shot jets installed, so I have my SCI to retard the timing 4 degrees, then if I ever wanted to go w/ a 75 shot, i'd retard it 6 degrees. if you are gonna run a 75 shot, DEFINATELY upgrade your fuel pump. I got a Walbro off ebay & it rules. the ZEX site says you don't have to, but it's just a good idea. Also, if already running a 94 octane fuel, octane booster isn't gonna do jack. It might bring it up to like 94.3, but nothing noticable at all.