The 160 ran last summer on the same pipe? Then it could have build up since last summer?

It could be something inside the Hatori Pipe...Do you have another to try...or just run the engine with a header only to see?
My thinking is it could be carboned up or blocked.

What fuel? is the question if its been Cool Power all along then its not likely the carbon build up. I have not seen it in running the CP since 2001. But I know lots of guys last summer had an issue with a specific fuel.

Just curious if it was that?

Troy