Barrel length and other stuff

So I have a JM Gen9 and want to upgrade to to mainain accuracy but also punch a lil harder, I’m assuming a 1.3 spring would be best but not too sure. Let’s say it 1.3 is best what would be a ideal tightbore barrel length. Also what else would be worth upgrading to maintain reliability, would nylon gears hold up to a 1.3 spring? One last thing, is changing out the motor worth exploring? Cheers.

I have found anything over a 1.3 spring is difficult to maintain decent accuracy plus anything larger will require metal gears, bearings and a 3s Lipo as a minimum.
My favourite spring is 1.25/1.3 unequal.
If you want a bit more punch just go with that plus a good o ring and a DK hop up.
The nylon gears should be fine.
If you get a tight bore barrel get the same length as the stock one and be sure to get a genuine t piece fitted, I have found most upgraded t pieces cause issues feeding and crushing gel balls.
Also with the tight bore barrels you need to choose or control the size of the gel balls carefully.
The stock motor is fine on 2 or 3s unless you are looking for higher rate of fire but that comes with issues aswell.
If you want a fantastic barrel have a look at the Bruisemaster ones and ask them to fit the t piece for you.