Battery and upgrades

Well I'm not exactly sure if this is in the right section, but I didn't know where else to put it.
So I was if someone could link me to a fitting 9.6v battery (preferably intellect, I'm most familiar with those ones) that would be great. Had a bad experience with the battery with the gun before this and ended up returning it and getting this one specifically because of that.

I was also wondering if someone could link me to a more powerful spring and a tighbore barrel for this gun. From the description its spring seems ready to be upgraded without any prerequisite upgrades, but correct me if I'm wrong. And I was looking for a 6.03 tighbore if anyone knows of one.

http://www.airsoftgi.com/product_info.php?cPath=139_24_160&products_id=4878

thanks!

The battery is in the handguard right? Just making sure since the KV stock has the ability to house a battery..

Try this http://www.airsoftgi.com/product_info.php?products_id=3372

Springs: 350 - 380 fps ; 380 - 410 fps

I think this barrel should work.
http://www.airsoftgi.com/product_info.php?products_id=6072

I have that battery drummer posted, and it is amazing, also it is small. so it should be able to fit inside that hand guard no problem at all

For the gun I'm getting the battery IS in the stock. I'm sorry for not clarifying. So I'm not sure where to start looking.