Whoops, I should explain better. The bar I got is like a comptech one. (yeah, it's an ebay pos *shame*) That means it mounts on the chassis NEXT to the pillars... where the factory has the pattern for drilling the bolt holes. The pillars on the EK (that's 6th gen, right?) have a big flat space between the pillar and the sidewall which is where a strut bar can be mounted. Since it's independant of the suspension, that's why I could loosen the bolts.
I'll try to get pics up.
The only thing I could think of is that, following the comptech install instructions, I drilled the 3/8" holes and used 8mm bolts (yeah the bolts are the perfect size for the bar). However, since the 3/8" holes aren't a perfect match for 8mm bolts, there's play. I think during the turn it caused the bolt to slip a bit, and therefore the vibration. Maybe I need some 8mm washers.
I don't race with my car... I just wanted to make it more fun to drive.