I just want to add and again im not trying to be an a hole or insult anyone and I am sure im gona come off here as arogant and an a hole but this site http://home.wanadoo.nl/pereivers/ryobimods.htm is one of the prime reasons this thread was started. he does give some datta but makes no sense at all to me anyhow. From what i have seen he dosent have a single engine turning over 7000 rpm. guys here are getting good 7500 rpm results with not much mods at all and darn near stock engines that are well set up. mines turning 7400 rpm with a dynathrust 18-8 and his is only turning 6400 with a 18-6 dynathrust prop. 2 deg less pitch and it still wont turn over 7000 rpm. hmmmmmm interesting huh.