The limiter is set for 150*, but at those speeds the speedometer could easily be off by five or so.

I've been to the limiter a few times (3) and haven't noticed any hood shaking going on.
Check to see if the hood bumpers (small rubber pads at the front corners) are adjusted evenly and don't allow the hood too much free play.

*At least the ones sold north of the border are.

Matt