Thanks Will,

The plane really is extremely well constructed and finished. Wish I had the skill-set and patience to build one of these MK classics. I'm afraid we all have gifts in life and mine is not fine model building - ARF's OK, but not stick building etc...

I could have took the easy road and left the std. YS .61 in there that came with the plane or changed it out to one of the AR's I have which I believe would be correct for this period and plane, however I love the sound of short stroke on the pipe - reminds me of when I was a kid starting out in pattern - thats all there was.

The modifications are not a big deal to fit the YS 60 FR and header pipe, just a little time consuming to get it right. Also the grass field that I fly on makes it really tough to swing a 12" prop without mowing the lawn. May even have to try a 10x10 to 10x12 apc to get ground clearance. Pavement is a good hour and half away !

The only problem I am having is identifying the Hatori pipe I have - it measures aprox. 17" from end to end which I believe rules it out as a Hatori 601 and makes it either a 650 or 700. Its the old style smooth tapered finish no ribs or bumps where there are baffles. Hopefully someone can definitely state exactly what the end to end length is for each of the popular Hatori pipes (ie 601, 650, and 700).

I did find some information on line, but there are some conflicts in the numbers - note the 700 length dimensions differ.

Any help is appreciated. Attached are a couple of picss with sizes, but need clarification or confirmation of the same.