Upgrades for my brand new gun

ok, i recently bought a crosman Pulse R72 g3 sas. this thing is amazing coming out of the box. it shoots about 325 FPS and accurate up to probably about 120 feet. and to top it off, it comes with a plastic gearbox!!! im impressed with the performance out of that crappy gearbox. i am planning on upgrading all of the internals to systema, getting a 6.04 or 6.01 tightbore barrel, getting a 9.6v 4200 mAh NiMH large battery, and upgrading the motor. any ideas besides systema? (near same quality but cheaper?
all of the upgrades together i have calculated will cost roughly $500....

I just have one question. Why would you buy a cheap crossman gun, when you could buy a G&G, TM, CA, Echo 1 ect.... That would have saved you so much upgrading and money.

How about starting with a gun which won't eat itself alive the second you install any upgrades??

Jim

Unless you are talking about doing a complete GB Build and installation, don´t even entertain the thought of trying to upgrade a Plastc Gearbox, like The Jim said, this thing will self destruct and take most of your upgraded parts with it.