Most of you have seen the picture I posted of the Systema M120 springs. Well you got to see those due to my deciding to tear into my gear box. I installed a Systema M130 spring, Systema Flat Torque Up Gears and left the rest alone as it was already done. Since I'm using a very short barrel which is about an inch longer than an MP5 inner barrel I haven't been able to get the gun to chrono close to 400, best I think I ever got was 370 and that was with a TN 6.04 full length M4 inner barrel. So if my guesstimation is correct, I should be darn close to the 400 mark with it now. Now the interesting part is that I could not get it to cycle with an 8.4 1500mah battery. It would cock the piston back about 70% of the way and then hang. I put in my 8.4 2000mah battery and it worked just fine. I read that they recommend a 9.6 battery for Torque Up Gears but it looks like a higher MAH rating will do the trick too.
