Best is relative to what you like. some people like the fart can sound, some like quiet, some like deep rumble.
I have Glass Packs and like the sound. It had 40 series Flowmasters and that sounded really good. but the exhaust configuration that the PO did was stupid. Here, let's wrap the exhaust pipe under the frame rail and out to where we can run flowmasters as side pipes.
just depends on what you like. go listen to some and find a configuration that sounds good to you. Also, CJ5, 7...8 length plays a roll in this as well.
Ive got oem manifolds going into 2.5" into a single 40 series flow. Ive got a 3.5" Dump on it. I love the way it sounds, although it would be much better if id fix the exhaust leaks. oh and its a 360 but should sound similar to 304
Product: 942546OR
Description: Super 44™ Off-Road muffler offers a massive improvement in crush resistance. These heavy-duty off-road mufflers utilize the same technology as our Super 44.
Company: Flowmaster Inc.
Address: 100 Stony Point Rd.Suite 125, Santa Rosa, CA, 95401, U.S.A.
Phone: 707-544-4761
Website: http://flowmastermufflers.com
flowmaster 50 series. typical flow, less noise. I put one on my old explorer and it was just as quiet as the stock muffler. I have one on my 4banger yota with a gutted cat and it is loud enough to hear it but not enough to be annoying.