Hi, Coxy
That does happen on GTRs. I've had two pipe flanges break on mine over the years. At least you spotted the split flange - the first time it happened to me I spent ages messing round with new gaskets and exhaust sealants trying to cure the messy black oil leak all over the front of the motor. It might be worth checking your engine mount bushes. I can't be sure, but after my second broken exhaust flange I noticed the the engine was moving around a lot in the frame and on inspection I found that the front bushes had completely broken up. Possibly the knackered bushes were allowing the engine to wve around under power ad overstress the exhaust fittings?
It is possible to repair the old pipe if you can't get hold of a replacement. My local engineering shop trimmed off the old flange without cutiing off and pipe length and made up a "top hat" section ring which he then brazed into place. The flange on the "top hat" section was made rather thicker than the original pipe flange, it has lasted over 20 years to date.
Hope tht helps,
Graham
