My 09 foz has 300+ whp on the stock axleback muffler but has a 3" uncatted downpipe, equal length headers, and a straight through 2.5" midpipe with no resonator. Its definitely not stock sounding but remains very quiet on the highway and you hear no exhaust noise inside whatsoever at constant speeds. That keeps things comfortable.
I have swift springs and 22mm sways that make it handle great, but only cost me .75" of clearance. That makes it offroadable and great in snow and yet I still manage to run in the 12 second 1/4 mile range. Its ao much fun to be complete sleeper like it is.
Its like the best of both worlds. I dont get a second glance by cops, and actually have a hard time convincing the regular joe that its quick at all (till they go for a ride