After doing a ton of reading, I think I'm gonna get a Super Tigre to save a few bucks although I'd rather have the TT. I'm still kinda stuck at which ST .90 to go after. The G90 with its smaller intake passages and lower RPM/larger prop scenario or the S90K. Both seem to be readily available, but I'm bearing in mind of not having the ability to run props larger than 13" diameter. Would either have a problem turning a 13x8 or 13x9 at around 12,000rpm? That or turning up a 13x6 13,500-14,000?

Those rpm figures are just left-field guesses. I have no idea what they'd turn but I'm just looking for the best all-around choice. I'm not too concerned with weight or size - the engine is for an airboat. I'd like to have the ability to wind the engine up a little bit for a little extra speed and I've been seeing more recently the G90 not being friendly to say 13x6 and being recommended a 14x6 instead. Any thoughts?

How would either of these ST engines compare in power to my K&B .65 Sportster? Is there even a comparison?