Flowmaster
I am in the market myself and had good luck with the Flowmaster 60 series when I had a 2nd GEN 4Runner with the 22Re 4 cylinder. I am leaning towards a Flowmaster 60 again for my 99 but slightly upsizing the bore diameters (you can pick from several sizes of input/output of the muffler)
The lower the Flowmaster series number the more aggressive the sound. 60 was fine for me, the 70s sounded a bit wimpy, while the 50 was too much "bass" , again in my humble opinion.
Magnaflow also makes great stuff, though I am not sure if I have ever heard one. They also make and sell catalytic converters-and you could recoup some cost selling back your old cat for the scrap value.
Personally I would never do a muffler exchange without doing the cat at the same time. They do indeed plug up, especially if your truck is not allowed to run for hours on end, like a highway run of some significant distance. It's a cheap prevention of any problems while you are having the exhaust done properly. I used Summit Racing to find cats and mufflers to pick from.
I once had a lowly Mazda GLC that had 2 cats for some unknown reason for it's less than stellar 4cyl. and it was plugged enough to blow exhaust gaskets off the manifold, twice before it was diagnosed properly.
There are a number of threads on this and some include sound clips so you can sample what you want to buy. I would encourage having the downpipe (off the engine) enlarged to around 2 1/2 or 2 3/4 inches and run that diameter to the cat and then the muffler and out the rear (side) to increase performance.
And don't forget the impact of the O2 sensor-location/operation while you are at it....
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