Ive just fitted two more injectors in the top of my manifold the red standard ones
what should my percentage be? Looking at running 21PSI with an ITS 60/1 t3 stage 5 exhaust.Do you think the stock motor will like it?

 

If you're using a standalone, it's not very wise to add additional injectors especially on top of the UIM. You could install 4 1600cc and control them easily with the Microtech or any EMS. That is more than you'll ever need.