Oh its obvious what guys are runnin when they say it is a secret....gsr, which is very light, mainly why is quick, built the motor this winter, mods are a secret but i will tell you if you want to know
obviously you have HS built hollow cams with eutectic coated liquid silicon filled inconel exhuast valves, with titanium intake valves both from HS along with the obviously and well known intermetallic rockers which feeds all air to the Magniesium based pistons attatched to HS metal matrix composite con rods which finally turns the beautiful HS Forged Steel Crank. Breathes through Weekend Warrior Intake mani and exhaust header.
Did I nail it or what?
Oh and lets not forget the HS elastomeric bearing engine mounts.:number1