IE shit is cheap, and i've heard rumors (note: rumors) of their urethane mounts melting from the heat coming off of the exhaust manifolds. however, my personal experience with m20b25 mounts they made in the early '00s was good... i could grab that car by the intake manifold and shake it back and forth. but that doesn't mean they aren't going through a cheaper supplier nowadays.
anyway there is absolutely a reason i went to vorshlag for my camber plates, so i don't doubt you did the right thing, and i will probably go the same way since i turned around a couple grand selling parts this weekend, and i'm tired of feeling my drivetrain flopping around now that everything else is so tightened up. my car's already too loud to have a phone convo in because of the exhaust, so i'm not losing anything.
that was gonna be my guess also; just put preload on it and call it good, but i figured i'd leave it to the people who actually made it.