I also have too much money into my Ryobi. I've had it for 3 years, and can't stop tinkering with it. I've got one of the models without the compression relief slits in the cylinder wall, and I recently swapped in a newer 2 ring piston. I would be suprised if any new ryobi's still come with the single ring piston...
Currently, it has C&H ignition with syncro spark, a free-breathing after market exhaust, and I just swapped on a larger bore carb as well. I picked up one from Ebay whose bore matches the transfer passage in the backlplate. It's a Walbro WT-433 with a 5/8" bore and 11.1 venturi. As noted above, I opened up the reed valve. Current RPM's are 7550 with a 18x8 APC wide prop. This engine just gets better and better. I'm trying to locate a Menz 20x8 but haven't had any luck finding a source.....
You guys who wanted to see a hovering Ryobi might just get your wish!