The two best props I have used are the MA 14x6 and the APC 13x8. I have been running ST 90s for 15 years. You will not hurt the motor. If BAX post on this forum he will tell you to try something smaller than I run. He seems to like his Tigres to turn more RPM. Nothing against his advice he knows his stuff. I just have better luck with the two I mentioned.

David