Damn Mr. Impatient... Calm down there, Turbo!

Ok, a few opinions: LT's and an x-pipe with no muffs will be pretty damn loud. The only thing about exhaust and the resonating HUM is if you dump--anywhere from the headers to the end of the tail pipes. Some people say dump them after the rear axle, but you will still get the annoying drone. Adding Dynomax bullets will not cut back on your horsepower at all. If it does, you will not be able to feel it because it may cut back 1 or 2 hp... Mufflers are designed to do one thing: Quiet down exhaust noises. Nothing else. Some say that it helps with back pressure to "create" more horsepower/torque... Each performance muffler is going to give you a good sound with excellent flow. Have you ever been in a truck that has dumped exhaust? If not, I'd say go for a ride and see what you think. Some people say having dumped exhaust is about as cool as driving a Jeep Wrangler around: It's cool for about 3 days, then it gets annoying. Some really like the sound and it never gets annoying to them. Others say it is annoying---and have to worry about what the wifey says, and have to worry about the kids... Do what you want---since you mentioned DynoMax Bullets, go ahead and do those with LT's, no cats and the x-pipe with tips behind the rear tires. That "sounds" like a pretty good setup...

As for the O2 bungs...the front bungs on the LT's will fit the O2 sensors just fine...just make sure to have Allen disable the rears--it's no biggie for him to do that. You may also want to consider driving to Allen's shop and see about him doing a live tune to make sure he gets the A/F ratio just right...