3000 rpm vibration
 

I recently have purchased a 2000 Boxster standard (2,7l,5spd). I am observing a noticable vibration at 3000 rpm. At the 3000 rpm level I experience the issue. I do not get a clunk while shifting as I have read from other descriptions of front motor mount failures.The vibration is mild but very annoying to me. Does anyone know if this is a clearcut front motor mount failure or should I be looking elsewhere?(47,500 miles)

My 2000 2,7 has exactly the same problems , sometimes less and sometimes more.
Front motormount exchanged whithout success, Dual mass flywheel also exchanged.
Problem is common and even one authorized mech told me not to bother because they they could not fix it.
I have noticed that vibrations changes depending on what muffler I use.