How far to rev this 273 commando build

Well , I got around to installing my new dynomax ultra flo mufflers on the fish today . off with the flowmaster 40's.
ultraflos are are quieter at idle...........
The drone is gone at 35 - 50 speeds. but ...... when you run thru the gears with rpms shifting at 4000..... there are all kinds of different sounds coming from these mufflers. It's weird. and when you get on it real hard, it rattles your ear drums . The flow masters were quieter when you got on it hard .
I have to drive it a little while longer to get the feel of them. They do have unique sounds for sure . I might have to ad the h or x pipe.
mufflers are dumped in front of axle .