if you use ANY metal gasket (WRC or Cometic), then you WILL have to have the head and the block face machined so that they are 100% flat.

the fibirous gasket (group a) will help "mask" any imperfections in the head or the block face, but a metal one cannot.

how much boost do you run and are you sure the gasket was fitted correctly the first time, as i ran a standard YBP head gasket for over a year with no problems at all, at 20psi on a T34.