Way to completely screw over the topic buddies.
My school of belief is never put more stress on your AEG than you need to, so a LiPo for a weapon I don't need it for seems rather ridiculous. A few more RPS is negligible in the type of airsoft I play. Ask me about my VFC SCAR, and I would love to get a LiPo for it, because aftermarket battery space is non-existent, and the gearbox holds up decently to a LiPo.
The story of this thread though, is what is a good idea for the OP to get for his stock G36. My suggestion is a KV stock, because even then, rewiring a deans LiPo to the back is a great idea if he decides to take the LiPo plunge. Still helps the balance, and the SRC should be available through certain retailers (Don't do Evike though, overpriced and most likely isn't in stock, contact TSD directly for info!).
My first upgrade though, as for any AEG that isn't a super/ultra high end (VFC/Systema), is to get a nice tightbore for it. It will help your shots much more than any FPS or ROF will. A new hopup unit is a good idea too, but thats not as immediate. The KV stock is my personal upgrade of choice beyond tightbore though.