[avsfan733]

Not quite sure if this belongs here or in the tech forum but the mods can always move it.

I have read that the engines in WRC cars the engines have a "anti-lag" system on the turbos. Knowing what i have read and what i know about turbos, I am assuming that these are something more mechanical then a well designed set of impellers. The way i understand the systems used no, they work by severly advancing the ignition timing so that the exhaust valve is open during the power pulse to keep the turbos on boost when shifting.
1) is this correct?
2) why do it like this?
3) couldn't a seperate gas injection system be better and easier on the engine?