im not sure if you have a rear o2 sensor that sits after the cats, but if you do theres a way to get around it. i cant remember exactly what its called but it screws between the bung and the sensor and the distance tricks the sensor to think its all runnin good.
i have 2 in my 5.0 followed by a glasspack duals out of it and it sounds way better than my buddies who has no cats at all and a flowmaster single out. the cats seem to give it a deeper sound and alot smoother of a sound too. but its your truck so dont let me keep ya from doin what you want
heres a post i read from google
"I'm not going to ask why you're doing this, but I will tell you that unless you have other serious mods, you gain next to nothing by doing so. That being said, the best thing I've seen people do that actually works (I'm a PA inspection mechanic) is going to advance auto/auto zone/whatever and buying two(2) SPARK PLUG foulers. Drill them out to accommodate the tip of the rear sensor, screw them together, thread them into the factory bung in the exhaust, and then re-install the factory sensor into that apparatus. It sticks out kind of far, but thats the idea. This way, most of the gas goes right by the sensor location without being read and only a small amount will reach the sensor, tricking it into thinking the cat is working. If you want to read up on this just google it. It's everywhere, as this seems to work across most makes and models (I first saw it on a Honda forum). Some have only had to use 1 fouler, but most report that it only works with 2 or more."
that thing is essentially the same as a glasspack, just chrome, not cherry bomb red. i would leave the cat together personally,and run that. It'll give you more the sound you want i think, i dont have a cat, and just a muffler, and wish i had one. My truck has kind of a bad sound to it. plus if for some miraculous reason you happen to get emissions testing like where i live, it just shows up, you wont be screwed in the long run
so you are saying keep the stock cat and run a decent muffler should give you a good exhaust sound. how is this?? the cat cuts down on the flow of exhaust, just putting a different muffler doesnt sound right. maybe a glass pack because its a flow thru style. dont think this would work with flowmaster or thrush mufflers. i want to do a single pipe exiting out the stock location just bigger but want a little more tone out of it. any suggestions???????? not trying to hijack ur thread.