Most likely for now upgrading your gun wouldn't be very necessary, I have seen people with JG's use them (stock parts and all) without any worries. With that said, it may be unnecessary to even upgrade your gun till it breaks.
Now however if you still feel the need to upgrade the spring (Nothing wrong with that) keep in mind you may need other new parts like a cylinder, or motor. You can read about it in the FAQs and Upgrades/Modifications thread.
*What I do recommend though is that if you do upgrade the gun, GET A GUN DOCTOR to do it for you! A list of them can be found on the top section in the Forum's Doctor's Corner Thread.
BTW for the silencer, you may need a silencer adaptor due to the length of the gun's threading being too short, to the gun's handguard. Now I am not 100% about this so I'd look into that as well.
Last edited by Short Round; October 17th, 2010 at 10:00..