>> I looked at the engine mount and I will need to move the YS63 back because of the prop hub position. If you think it would be okay then I will go ahead with that.

I don't know what kind of an engine mount came with the plane. Therefore, I do not want to comment on that.


>> Do you have a recommended source for the Hatori flexible header and the silencer?

Unfortunately, Hatori stopped making those flex header for a number of years now. However, you can contact Central Hobbies, they may still have some older one in stock. Otherwise, they can give you recommendation for an alternative for your 63. I think your easiest solution is to use a cigar shape muffler that comes out on the side of the nose of the plane, and you don't have to worry about broken flex header & soft mount it.

You can also take a look to see whether you can fit a Hatori # 643 header - http://www.centralhobbies.com/Exhaust/hatheadr.html, along with a Hatori # 720 pipe - http://www.centralhobbies.com/Exhaust/hatori.html. Both from Central Hobbies.

However, it will not be cheap, & may take quite a bit of work for retrofitting.


>> I apologize for asking these basic questions, but what do I need to "soft" mount the header and pipe? Thanks.

No need for any apologies, that's how I learned when I first started flying pattern - some 15 years ago - by asking questions. Here's a link to the soft pipe mount - http://www.centralhobbies.com/Exhaust/clamps.html#hush

Let me know if I can be of further assistance.