Your best bet is going to be a flowmaster 50 series or 70 series muffler. Those won't have any drone and should sound pretty good when you step on it. I run flowmaster's cat-back kit they make for these trucks, which comes with the 70 series muffler. There's no drone at all, and it sounds pretty good if I get on it.
A flowmaster 40 or 44 series would most likely be too loud for what you're looking for at lower RPM's. Ultimately, you will never get something that sounds quiet at idle/low RPM's and then something that's loud when you get on it but I think the 50 series and 70 series mufflers do a pretty good job.. I wish mine was louder at low RPM's, but that's personal preference.
A 50 series muffler will be louder (albeit not by a ton) than the 70 series.