hey graham,
yeah, with the stock cylinder and head installed, i was getting a slow leak of black oily junk from the head gasket area. from the limited riding i've done with the new cylinder it looks like the metra cylinder and stock head it looks like i still have the same black oily leak.
i think it basically comes down to the decomp nub area not sealing quite as well as it should. some of the oily discharge that would end up in the exhaust gets diverted a bit into that decomp hole.
here's a slightly better picture of the stock cylinder that shows the leaky area.
<a href="http://www.flickr.com/photos/uhoh/2458007556/" title="DSC_7738x by uhohphoto, on Flickr"><img src="http://farm3.static.flickr.com/2070/2458007556_6aa7839db2.jpg" width="500" height="333" alt="DSC_7738x" /></a>
![http://farm3.static.flickr.com/2070/2458007556_6aa7839db2.jpg"](http://farm3.static.flickr.com/2070/2458007556_6aa7839db2.jpg"){kind=link}