Draw through system is much more simple it eliminates the use of a inter cooler and some say its much easier to tune the carburettor for it than it is for blow through.

its simply just like a normal turbo setup but instead of the boost going through the carburetor (like blowing in) thier is a carburetor places on the intake part of the turbo which suck in the fuel and blows it out to the inlet manifold.

it shuld be as effective to blow through to some extent (because of no intercooler) but as mentioned water injection can be used to cool the incoming air.

these links should help.

http://datsun1200.com/modules/mediawi ... hp?title=Forced_Induction

http://datsun1200.com/modules/mediawi ... p?title=Topgear_A12_Turbo

The topgear one uses a suck through system.