Here is stock vs Milltek non resonated:



The Non Res has a good bump in sound over the res, see if you like that sound above.

 

I'm old school so I go about things differently and decided I wanted more power and still retain a reasonable amount of decorum so I decided it was straight pipe all the on my '06 MCS. I cut off those stupid dual mufflers and raised the trunk (oops!) boot floor to accomadate the battery and still have a FLAT floor. Ran a straight pipe into an Edelbrock SDT muffler - single inlet/outlet @ 2.5 diameter and used Corvette twin outlet tips. Sounded real nasty when you got on it yet no droning @ 75-80 MPH. Dropped 1/4 mile time by 6/10 so something must have worked right. As an aside I also drive a BOXTOP FAIRMONT with a big (510 cu.in.) Ford that knocks down 10.8 @ 128 consistently with 2.5 exhaust thru the mufflers.

 

Lucky to have no drone with a made at home exhaust, most I heard drone like crazy at 70mph.