Plugs, none other than NGK coppers, one step colder than stock. As far as fuel mods go, a b&m FPR would be a good addition to complete the setup and allow for further tuning. A purge kit is a good idea to keep fresh nitrous at the solenoid, get bubbles out of the line to keep consistent nitrous flow, and to clear the lines of any nitrous after the bottle is closed. A heater is also a good idea, optimum bottle pressure is 900-1050 psi. Below 900 doesn't make good power, I like to spray at 1050 and feel a big kick The heater will keep the pressure in that range. Since you have a vafc and have used the fuel tuning of it, you may want to get the nitrous tuned on a dyno just to make sure.