X-pipe or true dual??

From Car Craft Magazine. Finally, we swapped on the stepped X-pipe setup and were impressed to see power levels equal to the open headers: 335 hp at 6,300 hp and 302 lb-ft at 5,200. That’s a gain of 12 rear-wheel horsepower, although it turns out we weren’t really giving anything up or gaining anything extra from the open headers. So the car’s happy, and our ears are even happier!

Full article http://www.carcraft.com/techarticles/exhaust_system_installation/index.html