Saw elsewhere that the third cat was basically a concession to calif. epa and of no use beyond that. while I had exhaust off just drilled into the ceramic and broke it up and removed it and all the asbestos looking outer wrap, ended up just a mini expansion chamber, Started truck with it cleaned out and exhaust removed just for sound check and to blow out any remaining debris that may have gotten into pipe from my work, actually not very loud the two cats do quiet it down a lot, re-installed oem exhaust and drove for a day while my gibson arrived, sound was not much different than stock. Put the Gibson on last night (only have cell phone to video so no sense trying to post). Idle sound real good, v8 mode in all ranges sound real good also, not raspy and better than the video gibson puts out about it on you tube, V4 mode is noticable easily whenever it switches over to it, at low speeds it sounds like a V8 in V4 mode more noticable to the back seat occupants, over 60 it is easy to tell if its in v4 but not as noticeable and easily ignored. Still quiet in the cab a cruise on the highway and nice throaty tone when getting up to speed and kicking it down. Over all first 100 miles of it I like it more than not, the oem exhaust was to quiet and this sounds great, mixed feelings on the v4 mode sound, wish it was selectable to turn on or off as the range module is stupid expensive for what it does. Wonder about engine longevity with the v4 mode also. UPDATE: pulled battery cable to let engine reset and hopefully recalibrate for the exhaust, When last updated at Dealer took a while to get back to regular mileage etc. will post after a few hundred to see how it turns out.