No you dont have to remove the manifold to replace gasket, but honestly there could be several issues goingon that you not seeing.
First off was stud on manifold that broke fixed?
second it could be the.wrong ring because im not sure if the diameter, is the same beteen the2 engine(sohc & dohc) that would be the biggest difference
or third it could have been seated improperly
fourth would be engine vibration broke a bolt at that point and created a gap at the ring(this also play into factor because of #1).
Me personally I like a loud car so long as it doesnt aound like a tractor :)