AF Clubman issue

[St George]

Today I fitted an AF Clubman to my SIL 200 engine, runs very nice. But only less than half an inch of the exhaust reaches the inside of the silencer. Not ideal at all. I have slackened the manifold nuts but there was no more play. I am considering welding another 3/4" of tube onto the pipe. Has anyone else had this problem and managed to resolve it. My barrel has a 3 mm spacer but I don't think that this is causing the problem. Cheers.