Old post I know but for anyone else looking into this gun.
I am and have been running the VFC Scar-l as my primary for a while now. You have a ported cylinder that will max out on a 407mm tbb if you were thinking of extending the barrel from a 363mm. As for the internals/wiring I haven't had a problem with it yet. I run 7.4 Lipo sticks in it since the battery compartment is a tight squeeze but if you do not run on full auto they tend to last me a LONG time. When I run on auto I can get about 4 hours of heavy play out of them. If you want to get a bigger battery you could consider getting a mosfet or as already said replace the wires and go to deans.
VFC does have the self shimming gears I know that people have mixed feelings about this and I plan to eventually change them out but that wont happen until I start having issues with the gun. I crono at 389 with .20g and I find that running anything under .25g isn't worth it.
Upgrades: Other that tossing a RDS and a stubby grip on it I have only added a 407mm 6.03 tbb with r-hop, I use a suppressor to cover the inner barrel as it will come about an inch past the flash hider. That has the gun cronoing at 400 fps (400 fps is my field limit). Why only an 11 fps increase? the stock barrel is a 6.04 tbb brass barrel which is sufficient for field play but I do sims and when you are trying to really reach out and touch someone the inconsistencies in the brass barrels just won't cut it. I ran the gun for a few months on the stock barrel and it did just fine but the barrel, and hop-up would be the first things I would replace.
General Mods: When I first got the gun I tore it down and checked it out. The good news is you can take the cylinder and polish the hell out of it and with Teflon tape make 1 hell of an air seal (there are some good guides on airsoft society for this).
The inner and outer barrel fit very well together and I have had 0 vibration but if you really want to you can use grease to get rid of just about any vibration you could have.
In the end I like the Scar-l a lot I think it is a very good platform to work from. My biggest complaint is the battery compartment is so small that you truly are limited in what you run. My DMR has 1 battery that I can run an entire weekend and never have to charge it and I shoot all the time, you simply cannot do that with the stock on the Scar unless you run the wires outside and mount the battery that way. I would recommend doing the basic tuning of your gun (guides on airsoft society) and putting in a nice steel barrel and you will likely be very happy with the gun.
