OEM Replacement Exhaust

[mercdudecbr600]

Hi All, due to corrosion, I'm on the hunt for another decent OEM replacement muffler and tailpipe. As a primer, at least in the early KJ's, the muffler doesn't seem to be an exhaust restriction (the front Y off the upper cats is a very inefficient design - this got revised in 2003/4 I believe). If you were going with headers and hi flow cats, that's another story. And, the front Y and cats appear to be at least SS t409 and maybe t304. The back tailpipe including the muffler is probably aluminized judging by the range of surface rust I observe.

So, here is what I've figured out for those of us that need a OEM style system and want a quiet ride (the holy grail of exhaust):

1) 20" case dynomax super turbo muffler. Good flow and is very close to OEM sound. This is my general go-to muffler, very hard to beat. Seems to help (a little) with high RPM at full throttle runs, but not much else. Been running one of these for a few years with stock exhaust pipe. Sounds a little mean at cold startup but it as warms up the noise dissipates into a very pleasant/quiet OEM style sound. No drone but a little white noise at freeway speeds. Very good aftermarket option but only aluminized and longevity is limited.
2) walker quiet flow SS muffler. This is a very restrictive muffler. Even when upsizing to a dakota 4.7 muffler (2.5" in/out), necks down to 1 7/8" ID internally (though they 'say' it only necks down to 2"). Aluminized pipe, only SS shell wrap. To boot, walker part #54441 for tailpipe is crinkle bent and measures 2" diameter. I'd stay away from any of those options.
3) BRExhaust (magnaflow) direct fit system. Including options for SS and mandrel bent tail pipe. A little spendy but can be installed in the garage at home which omits muffler shop costs. They "say" it is 2.25" internally throughout. Upon physical inspection, I can see a very small necking down but I'd bet it's a true 2 1/8" ID. Tail pipe has nice mandrel bends. This seems like a good option and I will be installing one shortly.

Hope this helps the community.

 

[u2slow]

The stock pipe is a nice 2.5" mandrel bent piece, that necks down to 2.25" at the muffler.

I'm onto my second used tailpipe because the jobber Walker piece was a terrible crinkle-bent thing.

I'm running a cheapo stainless muffler from rockauto. That's after rusting through a welded chamber style 'flowmaster' knockoff (from Thrush). It is louder than stock but with a manual trans is nice to have some sound feedback instead of having an eye glued to the tach.

 

[mercdudecbr600]

For the 02/03 with the upper v-clamp cats, the front Y (at the left exhaust bank) makes a 135* upward/right bend to cross over the trans to join the right bank at the Y. That's horrendous for flow, even mandrel bent. And don't get me started on the exhaust (log) manifolds. I mean, even I-4 toyotas have short style headers from factory. Based on that unscientific analysis, the muffler is not the limiting factor for this vehicle. I'm also guessing that post cat the exhaust gases are cooling and therefore need smaller pipe to keep flow up, at least with stock level CFM.

That walker tailpipe is horrendous!