P90 upgrade question
 

I plan to upgrade my p90 with a m4a1 length tightbore (6.04) barrel, a SP85 spring with steel bushings. overall that brings the fps to about 317.5 fps
my question is will a 8.4V battery suffice?
also about shims i watched the mechbox.com upgrade video, they talk about the spacing of the gears. after i install metal bushing, will replacing the old shims be fine or do i have to add more or remove shims to get the right spacings?
thanks in advance Curtis

If it's your first time doing upgrades, most would suggest to get it done by a professional, and ask if you could watch on the side to learn your way around.

ok, but how about that battery?

i run an 8.4v in my tm m14. I currently have a 170% PDI spring, metal bushings... and some other fancy stuff but no need to go into detail. an 8.4v will work.

i guess that answers it thx Newby

You probably use a 8.4v Large, but the P90 can only take 8.4v mini.

With a SP85 spring, you'll have no problem with a 8.4v mini.

that works out perfectly:D thanks again