Ruski-
Yes it's a Bisson pitts, and yes it fits, but you will have to be VERY creative with cutting and notching the cowl, and cutting a bit more than one would normally feel comfortable with. I must say that the lay up on the cowl is exceptional, and it's plenty strong, just kind of a pain in the rear to get the cowl on and off with this muffler-

If you (or anyone else sees the pics with it in the plane, and decide to use it, the key is to make a day of fitting, cutting, marking re-cutting, re-fitting, etc, etc, until you have taken JUST BARELY ENOUGH material to make things work- It is paramount that you leave as much cowl as possible so that it retains its integrity-)
I'll post some pics when I have the chance- I am still recovering from the planes first "off runway landing" as I screwed up today and (a,) never set a high idle after takeoff, and (b,) slammed the throttle shut while on the smoke. I have noticed that the couple hundred rpm you will most likely lose from the smoke will transfer back to idle if you are abrupt with it- My assumption is that the smoke oil expands as it is injected into the muffler, and creates a bit of back pressure thereby reducing the overall rpm output- anyway, like the other bunny that I have, its a strong airframe and took the impact pretty good all things considered. just a touch of cosmetic damage, and the only structural damage was the right LG leg mounting plate in the fuse is fractured. all in all considering the wet weight of the plane (20+lb) It faired VERY well!
The first one always hurts.