hopup is an AUG unit.
I bought the g&g max version of the gun. I believe it has that upgrade cylinder head already installed. It also has something that piston and similar piston head, the head I think looks a bit different, but it is similar in style. I can't tell you for sure, I didn't look that closely at it when I opened it up. I did recently put in a standard CA poly carb piston with all metal teeth. I removed the first regular sized tooth like the factory piston and put in an m120 spring. The stock m100 and the original upgrade m150(I'm told) are about 1 cm longer when uncompressed.
Reassembled, mine is shooting just a hair over 400, which will settle under once the spring is broken in.
You do want to put a mosfet in asap, after about 8k-10k rounds my trigger block and contacts are starting to show the wear. The piston was starting to show some signs of wear along the teeth, so I replaced the piston as a precaution.
Last edited by lurkingknight; November 4th, 2011 at 19:29..