I've tried it over, under, and right-on. The general consensus is 1 to 2% over or under......so we're only talking about 22 grams......your bobweight being 2190........either side of hanging the calculated value on there. Just like balancing a tire/wheel, it is done at a chosen rpm. There are places they will have resonance that will come and go through the RPM range. The over/under ideas stem from the idea that the balancer can't simulate a "10,000 rpm, etc." condition, so we fudge it in theory to compensate. It is a WAG pretty much. I have never seen detrimental problems, or noticed the shake from 10, 20, even 30 grams one way or the other. I think the 150 g difference you have would make it shake right off idle, and on the way back down. If you rev it, it will go through the shake, and then shake again when it comes back down. Much like putting a 428 flywheel on a 390 or vise versa. It will shake again at some point, more violently if you turn it there, which may or may not occur. If it's really bad, one will shake all the time. Sometimes they will shake more and more often, depending on damper diameter, stroke, overall assembly weight, etc. If the machine shows it "out" more than 20g, we always fix it. I have changed pistons, rods, etc. on a known balanced crank up to 25 grams bobweight myself, and it is undetectable. I can't tell you more than that because I have never tried it past that.