predator500.. The 14X4W is a good prop for a 91. I have a Mag 91 4c
and I run the 14X4W with good results for me:-).. My Mag will spin a
bigger prop, But spool up time lags for me, And my engine vibrates
more and always loosen my pipe/muffler with bigger props... But
most 91's should turn a 15X4W pretty good IMO... The --X6 should be
good also, But I love the "W" props for what I'm doing... Or trying too