I shrunk most of the wrinkles out before putting the wings together. Then I took the plane out into the yard and let it sit in the sun for several hours to bring out the rest of the wrinkles. Those were shrunk down too.

All this was done before even taking the plane to the field.

Yes, stock G-45 muffler. Sound level was 89 db at 25'. 22-8 APC at 6800 RPM