I remember speeking with someone up at TRD about 8 or 9 years ago and they had a roller rocker setup in development for the 22r series motor, but for some reason that project was scrapped. I think that may have been the only thing that would quiet down that 22r tick - and maybe not even that. If they had a hydraulic setup it would definately be quiet, but that would require a entirely different head.
