I placed an article in the Show and Tell gallery about my GHL Exhaust Mod and how I got rid of the DRONE at 2700-3000.
The answer is CARCHEMISTRY! These guys have inexpensive baffles (Im talking under $60 for my boxster!) that are super ez to install and are user tuneable.
They may even add some low end grunt back to your 986 if your flow is too wide open (you lose power).
I have pics and more info in Show and Tell but I know that many of us suffer with exhaust upgrade drone - NO MORE!
Best to all!
GHL Exhaust w/Eisenmann Tip - w/Drone Killer!