Just finished reading it properly now, pretty good review, well written as expected . Shame about the feeding mechanism, it's the exact reason I didn't get one with realistic magazine placement, and I got the Well/Warrior over the Maruzen because it was cheaper and I've changed pretty much everything anyway..
The stock and bolt housing look much better quality than mine does, but I intend on replacing those two when I get round to it anyway. The rest looks on par, as I've replaced everything with PDI parts .
If When you get the feeding mechanism sorted and get it fully upgraded, keep us updated on how it's doing, will be nice to see.
Regarding the piston head, no it doesn't come off the stock piston. But with my LayLax piston, you need the accuracy cup head that pushes on the end of it. Otherwise you end up with a nice bit of metal sticking out the end where it clips on, and you have metal hitting straight onto metal when it hits the cylinder head.
And, when you upgrade the power, get a spring that is more powerful than you want, then cut and file it down. I got an sp170, giving 590-600 FPS, then cut it down to give me 495-500 FPS. This makes the spring last longer (as it's not being compressed as much, in comparison to full length and compressed length, if that makes sense), and it makes the gun much quieter because the spring is shorter so the piston isn't slamming into the cylinder head as strongly as having a full length spring.
If you go to the NAE 2013, make sure to bring it, I should be there, just waiting for work to make sure I've got it booked off (asked 5 weeks ago now!!).