not gonna play with stuff I dont know about yet... even the 13x6 I think is limits for this motor... I am gonna get a 12x8 and see how it goes... my plan is also to get the RPM up to almost 11 on ground... got it to 10500 with 12x6 rich setting... wanna get prop that will give me closer to 11 with the same setting... I gained 500 all ready from going down from 13x6 to 12x6 with the same tune...