are you talking bout standard 3T? if so then it is a 1.8ltr OHV carby engine. you can put twin side draught webbers and extractors on it for more power but the 2TG is a 1.6 twin cam engine that comes either efi or with twin side draught webbers. most will say the the webbers produce more power than the efi when tuned correctly.
also you will find that most people will throw the 2TG head and assortments on the 3T block to make it a 1.8ltr twin cam engine known as the 2T/3T hybrid
but stock the 2TG has more power than the 3T and thats obviously got more power than the 2T.