i've just had mine done as a maintenence issue, had the exhaust explode on the highway and threw a cat at a prius. had the second cat cut off and and straight into a magnaflow dual inlet open dual outlet. the muffler if you look through it is in an x-shape. as if it was an x-pipe inside a muffler. you can see right through it as it is chamberless. i have a bunch of resonace at idle but it sounds great throughout the rpm range. not loud but finally sounds like a truck.
kid a muffler shop had a good quote. said that some guys come in saying they want the same sound as their muscle car and demand the same muffler they have on their 19xx chevy/ford/dodge whatever saying it will sound the same, as if the muffler MAKES sound. they scream and yell when they are left with a truck that "sounds like 2 honda's racing down the street". ha ha ha.
fixing the previous owners mistakes . . .