New to Nitrous

It depends on the system and plate. You should ask the manufacturer for a starting point as in some cases 6+ will flood it bad. I used to run mine lower - 4-4.5psi. But they were smaller, and single stage. You will need to set that with both kits flowing - so take the plate and stick it over a bucket while you do it. It's also a good time to wet flow the NO2 fuel system to make sure you have the volume for it. I'm assuming you already have a dedicated pump/regulator for it. The instructions OmR posted says a tenth of a gallon per hour at 5 psi. I'd want to see twice that with the car sitting static, maybe more depending on how long the fuel lines are feeding the nitrous and where the regulator is.