Fitted one to my son's (Brucetopher1 on here), 660R. I ended up drilling the heads with a 6mm drill, then unscrewing the remaining threaded part using vice-grips once the head of the bolt is removed. You will need new bolts, hex head are fine as replacements. A BIG spanner removes the Lambda sensor, easiest to slacken it while the pipe is still on the bike - It will be tight. Fitting the new headers is a real fiddle, a ball ended Allen key makes life easier with the manifold nuts, the alignment of the headers is critical... and you will probably get a very slight leak at the sleeved joint, this seems normal and will disappear once the bike has run a few miles and the pipes have reached operating temperature.
You'll really notice the difference, and it sounds lovely with the MM pipes :-)

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