No worries, problem found and solved, was rocker cover gasket. For lack of a new one I'm using good old high-temperature Silastic, 'til I get the new enginehead in, when I can afford it. Anyway, thanks guys -- But I've got another question..
The exhaust leak is a real trouble, do R series exhaustpipes fit T series headers? Can I just plain fit an R series header/exhaust to my Celica? Can it be done?