99 Boxster - harshness/resonance at 2300-2400 rpms

[JoeFromPA]

Hi all,

I'm curious if my front motor mount is going bad (some resistance to shifting), and maybe this is linked to it, but I'd like to confirm this isn't just a normal resonance in Boxster's.

When engine braking, in ANY gear, from 2400-2300 rpms the car vibrates. In lower gears, it's enough to make some metal bits rattle a tad (i.e maybe a heat shield).

I've seen this in other cars where it's a natural resonance that occurs under a very specific circumstance and is no big deal. Was wondering if that's the case in the boxster 2.5 liter, or if it's more than likely something resonating because it's loose.

Thanks all