[PWR_RYD93]

Colder heat range spark plugs tend to load up (fuel foul) at idle and light thottle. Typically you want to run the hottest plug you can get away with (i.e. no detonation). With the amount of N2O you're talking about... one heat range colder is more than enough. You shouldn't have any driveability problems with only one range colder. I run 3 steps colder because of my high blower pressure and my plugs load up if I idle around too much. You should only need to retard your timing 3-4 degrees for that small shot. Rule of thumb is 2 degrees per 50 HP shot. And you'll probably need to reduce your plug gaps to 0.035 - 0.040" to avoid spark blow out. IMO - the dry system will be easier for you to get right.