Hello Tankers and other RCU Members - I am a brand new (this is my first post) both to these forums and to RC tanks. I purchased an upgraded version of the standard Heng Leng (Heng Long) M1A2 Abrams from Amazon that already has the metal (zinc I believe) transmission, drive wheels and tracks installed. Before I start to use it with my son, I would like to upgrade it to the best parts available for each function while still keeping it an Airsoft model. As of right now, with the small amount of reading I have been able to do, I have found the following upgrades to be well reviewed

Gearbox - the best gearbox I have found so far is the all steel and ball bearing models from Taigen
Tracks - the metal versions made by HL
Wheels and Arm Bars - the metal versions made by HL (my tank has the desert tan color, so I would like metal wheels that match that paint job)
Turret and Bottom Hull - not sure, ... I do not see a metal version of these for the M1A2 Abrams.
Barrel - I do not see anyone making a metal barrel for the HL Abrams
360 Turret Rotation Mod - not sure what to buy in this area
Realistic Recoil Mod - not sure
Smoke Unit - not sure, ... possibly the Taigen model is the best production model (?). I see many complaints about the HL stock smokers.
Speaker - not sure, Taigen makes a nice 3 watt speaker that many say is nicer than the stock HL version.
Motherboard - the Taigen unit that is sorta like a beefed up version of the HL RX-18 (not sure?)
Transmitter - the Taigen 2.4 GHz model (?)
Airsoft BBs - not sure but have seen some biodegradable pellets that look like they leave a chalk mark on the tank they hit
Battery - not sure, but have seen many nice 5000 mAh and 6600 mAh batteries that look like they would fit in this HL Abrams (but I could be wrong too)

Not sure, what else I may be omitting due to lack of knowledge. I am not interested in one off specialty items (let's say someone makes custom ordered carbon fiber hulls for the Abrams but they cost $800, .... not interested) but I am interested in starting off with a fully upgraded Abrams that will hopefully be around for years and bring my son and me a great deal of fun. If you can recommend other top end upgrades or correct what I have written above, I would appreciate it. Thanks! - Jay

(I have no RC modding experience but plenty of other modding experience and am an electrical engineer, so feel free to let it rip!)