The way I see it, I think there is a large factor that depends on tran/rear end gearing, shift points and tire size when applying more rail pressure. For example with 4:10's You turn about 17k at cruising and with 3:73's it would be about 2k psi less. And 90% of the time I'm not ***** to the wall. And someone correct me, but I believe a pressure box will only add about 200-400psi at idle and 1000-2000 at cruising? Of course running full throttle all the time will have a different effect. I just think there are a few things to consider before saying an absolute no. I personally run my smarty on stock rail pressure and add my pressure box as needed on the in cab ****, but yes be careful Injectirs aint cheap!

 

Yep. I ruined my first set of injectors with a pressure box. It cost me $4,400 bucks for a new set. I pulled out the pressure box and took a hammer to it. Problem solved! That could have been money better spent on a bulletproof trans. Oh well, lesson learned.