i'm using two nozzels, both are 3lph. activation is at 10 and 20psi. i would suggest doing your turbo and fuel before you put in the w/i. you don't want your tune to be dependant on w/i, because if the pump fails or a line gets clogged you'll go boom.
so i have heard you need stage 2 before you can do stage 3 but others are telling me you dont....so yes to stage 2 first or no just do stage 3...
You don't need Stage 2 before Stage 3, but you can upgrade from Stage 2 to Stage 3 if you already have Stage 2. Just make sure you get the right kit, Stage 3 comes as an upgrade kit for Stage 2 owners, or as a full standalone Stage 3 kit. The cost difference is something like $1200 or more, so it's hard to get them confused.