Okay okay, you want a high speed scar? I'm your guy
I recently turned my scar into a HS setup and now it fires 40rps @ 340fps
Parts you will need:
m100 Spring
Steel teeth piston
SHS ultra high torque motor
SHS/Super Shooter 13:1 Gear set
Shims, Lots of them
teflon grease
better gearbox wiring
Mosfet (this is a must)
6.03mm 363mm Madbull barrel (optional)
And a 9.9V LiFePO4 battery (I recommend staying away from 11v lipo's)
Work required:
Hours and hours worth of shimming & greasing the new gears. (this is the most important part of the entire set up, its a pain in the ass but if there is one wrong shimmed gear it will slow it down dramatically)
Greasing basically any moving part in the gun.
Swiss cheesing the piston slightly. (don't got ott with this i hardly did any)
Making sure the contact between the motor pinion gear and bevel gear is aligned perfectly, you cant afford to tighten you pistol grip too much/little.
Correcting angle of engagement.
Polishing cylinder head.
(optional, but i personally think its worth it) Hair Trigger
All the tutorials and tips to do all of the above processes can be found at
http://airsofttutorials.com/tutorials.html
By installing all the listed parts and doing the required work you will have a very high speed gun and instant trigger response.