Specna Arms SA-E10 Edge battery and spring upgrades?

[Twiggy]

So,

I am looking to buy this pretty soon: https://www.replicaairguns.ca/specna...-airsoft-rifle

it is about the most I can afford soon, but also means I'll be getting something nice for the money, right out of the box. For now, I do have a 7.4v 1800mah li-on battery to use with it, (from an unused RC boat).

Later on I do plan on buying a 11.1v Lipo battery for it. Can anyone tell me if the gear box in things thing will be good enough to handle a 11.1v battery without excessive wear and tear?

Also, I want as much FPS as I can get from this, so I will likely be using .12g bbs when doing backyard range stuff, and maybe heavier bb's for games. This also has the spring change system that makes it super easy to change the spring. I know it comes with an M90 spring in the box to make it shoot lower, but if I want it to shoot higher, can I get something like an m150 spring and just install it?

Also what are some of the most powerful springs out there? Is there one even better than m150?

[Twiggy]

For an update: I just went ahead and bought it, it just happened to go on sale today as well, so I saved a bit.

now, to wait for it to get to me. I'll be pleasantly surprised if I get it by Friday.