There have been quite a few ringed engines that could really scream, even after ABCs took over. I remember the LHS owner getting all excited about his Webra helicopter-to-airplane engine conversion when competition fun flys were the rage around here. IIRC, the heli version came out a couple of years before they offered it for planes and there was a choice between ringed or ABC. Hopefully the TT .39 turns out as good as the Webra and OS .32s, but for less $$$.