I have an 05 EVO GSR with Helix Intake, Full 3" Turboback with no cat, MBC set 21 PSI, and Walbro Fuel Pump.

I think I am looking around 300+whp based on other dynos. My question is: Will I be assed out on alot of horsepower just by doing mail-in flash. Or should i do custom tuning???

I would like to wait till cams for custom tuning but that will be a year from now.

 

Get the mail in flash for now and then upgrade to the cams and custom tune. Thats what I did and loved every minute of the mail in flash when I had the same type of mods as yourself. Definately do cams you willl not be disappointed.