From Flowmaster's web site FAQ page.
http://www.flowmastermufflers.com/?page_id=12583
"Do I need to install an “H” pipe in my dual exhaust system?
Flowmaster® strongly recommends using a crossover tube, otherwise known as an “H” pipe or balance pipe on all true dual exhaust systems. The crossover pipe equalizes the exhaust pressure and allows the sounds waves to communicate between both banks of the engine. Not only does this usually improve torque in the low to mid rpm range, it also creates a deeper mellower tone both inside and outside of the vehicle and helps eliminate “back-rap” on deceleration."
"Is an “X” pipe better than an “H” pipe?
Flowmaster® has performed extensive testing and determined that the “H” and “X” pipes generally delivers no significant difference in performance, but does affect tone. The “X” pipe will change the sound to a higher pitched tone. Flowmaster Scavenger “X” pipes however do increase power and torque through use of their patented D-port technology and retains the deep Flowmaster muffler tone that is desired by most performance enthusiasts."
As far as drone goes, I had massive drone from my super 44's even with the H pipe. I resolved it by taking a play from the Hemi cars playbook and used resonators at the tail pipes. In fact I used (simply because of preference) Jones 18" x 3" glasspacks on each side. Drone was basically eliminated inside the cab and pushed it all out to the rear where it should be. with no sacrifice in power or torque.
Here is a shot of them. my set up is 2" TTI's ceramic coated to 3" pipe to 3" flowbastard super 44's out to these 3" jones glasspacks to the OE tips. Its pretty calm at idle at a stop but man drop the hammer and holy smokes it's like someone just set of a baby nuke lmao J/K it's cool though. I have a video somewhere if interested I can dig up.
