I guess things are different on the XTZ. On the XTR, each downpipe has an aluminium(?) gasket at the joint to the standard silencer. According to the manual, when you take the pipe off, the gasket can be on the downpipe, or in the silencer pipe. If it stays on the downpipe, result! If not, you have to try to get it out and apparently that's not easily done without totally messing it up. As I want to re-use the standard pipes from time to time, the only option is to get a new set of gaskets for the new pipes.

BTW, I found a pattern part that is cheaper than the OEM one. Fingers crossed it fits OK.

http://www.ebay.co.uk/itm/Yamaha-XT-...item20c31b3362