first do you know how is mechbox work? can you open it up and put all the things back together and make it work again???
you u can't then don't try to do it yourself...
if you can then go next section...
2 side power (around 1.2J):
M100 spring
and nothing else you need to change...
but if you want improvement... u can buy HARD GEAR SET (any brand you like and base on your buget)
better Piston, Piston Head...
unless u want to change more (but this may make the airsoft over power...
