The spring is stronger, and the spring guide has bearings to reduce wear and torque on spring. The piston kinda sucks IMO, but it replaces the plastic one and is supposed to provide better air seal and durability. Unscrew the bolt near the bipod mount and the two near the magazine well. pull off handguard. open bolt and seperate upper and lower reciever. unscrew the trigger group and remove it. pay attention to how the sear inserts into the piston and trigger as it needs to go back in that way. You may have to loosen the two bolts holding the outer barrel in place. remove the bolt assembly by pulling the bolt out. unscrew the pison head and be careful as it is under pressure from the spring. pull out the internals and swap them for the new ones. put the springon the guide, insert, and then put the piston in. DO NOT FORGET TO LUBE! Anything I forgot?
Checkout E1's website for more mods and detailed instructions with pics. I also just did a review on the WELL MB06 which is the OEM of the ASR. look for it.
