I have run both the 3000, 3000k, as well as the 3250s. I sold my 3250 because the only prop I had that it liked, a 22x6 did not allow for enough prop clearance for its intended airframe.
There is a lot of bad, horrible and more bad advice on RCU on this engine. Dont even think of turning more than 8200 and getting any kind of good throttle response. You need to really load these beasts down. Not sure why loading them down improves throttle response, but it does. I run my current 3000k at 7400 to 7700 with a 19x8wide and 20x8 apc.
I tried the jett carb on my 3250 before I sold it and it was outstanding. Its pricy, 75 bucks, but you get just about DA 50 performance with it as well as it becomming a gas guzzler. I never got to try a larger prop than a 22x6 zinger (8800 rpmon it but I think it would have been comfy with a 24x6.
I've also heard of peeps changing the carbs, but these are the same folks using 18x8 (or similar size)top flight props. I've heard horrer stories about this motor but the secret is very simple, load the fucker down! If it farts on throttle up, you dont have enough prop on it.
Even in the OMP forum some guy recommeded a 18x6 on my 3000 to get better throttle response. Sorry dude, you are wrong! and that kind of advice is just killing the rep of these great motors.
oh yeah, people on RCU swear that you need to run an OS f plug "or it wont run" or some shit like that. Hes probably turning an 18-6 wide or some crap. Run just about any plug you like. I have had a K&B 1L in there for over a year now. And they also seem to run on any fuel. I run rich's brew ST blend, but I always mix in a little full castor fuel (just superstition I guess)
sorry for the rant, hehe. This is the only motor I feel qualified to comment on cause I love it soooo much.