yep, turndowns do help, especially if you aim them 20 degrees or so toward the sides. I love dumps, the tone is much more bassy and throaty. But the dreaded drone does get old. It's much more controllable if you have a manual tranny, cuz you can work the throttle or change gears to avoid the rpm/loads that drone the worst.
Interestingly, some combos actually drone less with dumps compared to tailpipes, especially with a 3" tailpipe. The sound just bounces around in those big pipes. If you think about it, a pipe of a given diameter and length is going to have a resonant frequency, the same as a port in the intake manifold or the port in a subwoofer enclosure. So it makes sense that there's a drone at a certain rpm for any combo of pipes/muffler.
Also, if you have longtube headers, the drone peak is not so sharp. It'll be spread out over a wider rpm band compared to shorties. That applies to tailpipes as well.