Terry, those numbers seem a bit low.

Stock muffler; 10% Powermaster; APC props:

12x8 - 10,780

12x6 - 12, 140

11x10 - 10,860

11x11 - 9,780

Mac's long stroke quiet pipe; 5% Powermaster; APC props:

11x10 - 11,860

12x8 - 11,910

David