Fuel burn is set twice that of normal. We don't have actual reserviors for the "go juices" because used with the fuel they would give you half the historical combat WEP time. So, we get the WEP limits the real planes had, but not the actual go-juices they had The weights are modeled in, as far as I know (on the Ta152 they are in one wing all the time), but this is a gameplay compromise.
G-14 and K-4 had MW50. E-4/F-4 just had higher settings, I think. I'm not sure (off the top of my head) about the G-2/G-6, if they had water injection or just higher settings.