RE: Ryobi 31cc twin ring & Frank Bowman ring
I have already taken apart a twin-ring Ryobi. The rings are indeed much better than the old single ring. The conrod is still stampped steel but has much larger webbing. The ports are also different and may contribute more to the power gain more so than an additional ring. Curiously the "decompression" slits are still there. Still, for roughly $25, the Bowman rings are not a bad bet, IMHO.