Is the ST 2300 considered one of the "Big Tigres"? If it is then adding more nitro and oil will likely not gain you more power...

Also -- most advice on Big Tigres say to prop them for the high 7000 rpms, 7700 or so... Although your next prop up is a 20X6 and that is the prop I plan to use with my H9 1/4 scale CAP and ST 3000...