I noticed that on many cars the turbo will only build up to a fraction of the max boost in neutral. This is problematic for launching and causes the car to bog down. Is there something I am missing?
It's normal. The engine does not produce enough exhaust gasses to spin up the turbo. If you want boost while in neutral you need a supercharger.
If talking about turbo build up it's right, but seems like turbo causes some unrealistic behaviour too. Look when you switch to manual mode in car with turbo and then trying to reverse engine will "stall" but it's interesting that this happen only with steering wheel, you actually can launch it but you have to keep your foot on clucth (~50% pressed) and full throttle, doesn't look realistic to just start, and too maintain speed you have to stay at full throttle, if you launched it and reached like 10km/h and let clutch or/and acceleration pedal off engine will "stall" too. Something similar but not exactly the same you can reproduce on keyboard, spawn i.ex. 89' Pessima race, set manual, full lock right/left and try to drive in reverse gear, no matter how long you will keep full throttle it will move only at engine idle speed (~1k rpm) if you'll set wheels to go straight it will launch like it should, then try to turn again and it will slow down to idle speed.
You won't spool a conventional turbo setup without some kind of load in the engine. Google brake boosting if you need a way to launch a 4wd turbo car hard.
I am aware of this but it only works for automatics or from a roll, I guess what I am wondering is if there is any way to implement some kind of antilag or launch control. Or possibly some kind of transbrake for automatic cars.