Yes. Go with stock.
If you absolutely must upgrade fps, aim for no higher than 350fps. 330fps optimal, and you can achieve that simply with a PDI 130% and metal bushings. (The EG560 Hi-Torque isn't that awesome of a motor.) The longer tightbore inner barrel is nice (I have a 6.03mm x 590mm in mine.

) as I find it makes for tighter groupings at long range.
-J