H or X CROSSOVER?

I ran a 3 inch TTi x pipe system on my 70 Dart with Dynomax super turbo mufflers and TTi's stainless tips. I found that it gave a really nice rumble during "normal" driving, no drone, and under full throttle much more noticeable growl. My wife never complained about the noise, my lead foot on the other hand................
I have the same results with my 3" TTI X pipe kit using Dynomax Ultra Flow mufflers with stainless tips. 550hp and no drone.