If you want to go fast using a .91 DF you might want to try control line speed props.
Go to
www.clspeed.com parts finder page.I am currently working with a 8x10.5 CF
prop from John Newton that I will be using on a Jett FIRE BSE 65 in a modified Diamond
Dust. There are several people on this web site that sell props, so you will have to make
a few phone calls. Generaly you will want to use props for D speed which are used on
.65 and larger engines. By the way these props are not cheap! The one I got from John
was $14.00, and still needs to be finished,but this is one serious prop! Hope this info is
helpful, and please be careful because it's hard to fly without fingers!!!!
Sincerly, Scott Romine