hey all,I have the GMS1 installed plus the Hahn catted s.steel downpipie on my 09 SS,runs real good but wondering if anyone with the GMS1 also had there's upgraded with another tune and if so do you see a very large difference in performance and if so how?thanks

 

If you get either HPT or Trifect on top of the GMS1...you will see probably an additional 30whp and gobs upon gobs of torque depending on your tuner.

 

I have the stage kit with full bolt ons minus the intake and im HPTuned on top of that. The tune made a real nice difference over the kit with bolt ons.