Yes, have had three sets and they work very well on all but the really high HP, high compresion,large cubic inch engines. Dynomax is working on the new versions for these more powerful set-ups.

We have a set on a low 12 second 360 powered 1968 Barracuda. They are very, very quiet at idle and cruise conditions, even with a 3.91. Once you put the coals to them, they open up and sound like the Welded UltraFlo.

We also have a set on Dad's low 11 second Pontiac wagon. They tend to be louder as they are not the new versions intended for big engines BUT they are still surprisingly tame for such short mufflers with such short silencing zones internally.

In both cases, there is NO DRONE. The Cuda runs tailpipes. The wagon has them at the rear with a shorter straight section of pipe following them.

Please also visit this string and read the data presented.
http://forums.performanceyears.com/forums/showthread.php?t=639125

Hope this provides enough data to help answer your question. If you are close to KC, I can help you install a set to listen to.

Tom