I've got the non-Delta 50 series on my 98 Sport. Even the non-Delta is still a little too quiet for my taste. The in-cabin resonance is annoying on long highway trips, which I take almost every weekend, but it's worth it the rest of the time. If I had it to do again, I woulda gone 40 series non-Delta. The 50 just sounds too muzzled for my taste.