A qualified No.
Since the WEP system uses an alcohol/water mixture for cooling purposes at high power, parts won't start "melting off of the engine" until the reservoir runs dry. Even then, in AH, your power automatically goes back to mil setting if the throttle is still full forward. The WEP system doesn't add power in an airplane per se, it keeps the engine cool. When the pilot pushes the throttle through a safety wired gate on the throttle quadrant, the extra throw allows additional manifold pressure and the resultant increase in power.
OTH
Extended use of nitrous oxide injection systems, as modeled in some LW airplanes, does directly add power by injecting a combustable gas in with the fuel/air mixture. The cooling effects are less than the US WEP and LW alcohol/water injection systems and may warrant a Yes.
MiG
[This message has been edited by MiG Eater (edited 01-19-2001).]