Ive got them welded in on my 01 Cobra.
They have a nice growl in gears 1-4, when you hit 2200-2600 rpm's in 5th the drone is kind of loud. More annoying than anything but it goes away. It is tolerable if thats what your looking for. No bleeding, ringing ears or anything. Quite aggressive in 2nd and 3rd at 2-5k rpm's. It turns heads.
well my freeway driving is almost non-existant so that isn't a huge factor (though a factor none the less.) How much quieter are the 40 series Delta Flows? As long as the DFs are significantly louder/deeper than the stock mufflers I would be quite happy.
I have had the delta 40's in both a 94 t-bird, welded in stock location, with tips that were about even with the rear bumper, and they droned worse than they did before my h pipe swap. I really dont see a big deal with drone, either my gears keep me above the drone mark, or I just love my offroad exhaust. If anything, I would switch out the deltas for original 40's. I do drive around 16 highway miles a day. Lay down the seats, and remove the trunk lining, and spare tire, and then I feel sorry for my neighbors, but that's just for fun.