Made you look!!!Actually, what we have here is a second gen on a new(Mazda factory rebuild)motor throwing a seamingly innosent( by piston engine standards) ultra slight variable vibration. At idle she's smooth, off idle she's close to norm, as you step it up you start to feel a bit of a "non teeth" chattering vibe, as the rpm's climb the vibration does also(and no, there is absolutly nothing rubbing on the body), but the wild part is at a few certian stops along the tachs way the vibe will actually stop,i.e.5,400 rpm, and again at somthing like 3,100. It seems to be flywheel related, or maybe clutch, I belive. I'm breaking in this thing real slow too, 60 miles at each 500 rpm increment, and I'm up to 5,000 so far. See the thing is I don't want to kill this motor too soon, seeings as thouygh our season has just begun. So the "BIG" question is... how much vibration is O.K., some,none or a whole hand full????? One more note, w/ a factory rebuild, you get a year warranty, so if this thing is'nt right I might just pull it and try again. ( depends on some of you Mazda cats insightfull advise) Thanks,Rick