it's all personal preference/perception...
they were too loud for me... which is a shame because I LOVED them for about the first 20 minutes or so of driving... about 30min into it, the honeymoon was over... about 35 min into it, I was looking for ear plugs.
if I kept the speed down in the 60-65 range, it wasn't as bad, but up around 70 it started beating on you.
the WORST was maintaining speed coming down a hill... 72mph, powering up a hill, it was a nice clean/crisp sound (still loud), crest the hill and give just enough throttle to maintain speed coming down, and the resonance was insane. this is with a couple hundred lbs of lead sheet lining the interior too
now, I've got a single cab 5sp... if you've got an automatic in that thing (lower RPM on the highway) it might be no biggie at all.
stacks are like an abusive relationship with me... I've run them twice, and they're sitting in the garage tempting me to put them back on. the just sound so good and turn so many heads, you forget about the pain on the highway (untill you're experiencing it again! LOL!)
Forrest