Hmmm..I thought the twin ring would turn an 18x6 a little better than that. I'm running a stock Ryobi(old single ring) with a paragon muffler and get 7100-7150 consistently with the 18x6. That's with either the MAS classic or a Top Flite powerpoint. I typically run an 18x10 APC on it to keep 4 stroking to a minimum. I get about 6400-6500 on that prop. Hauls my ugly 14 pounder around just fine. I agree, the Paragon kits are top notch. The only thing I don't like with the Zama carb is transition from low to high throttle is rather abrupt...but hey..it's a flyin' weed whacker !