7.3l exhaust wanted / help??

[DT444E]

Hello,

I have an 00 7.3 that i would like to improve the exhaust flow on but without the sacrifice of large amounts of money or ridiculous noise. I was thinking of 2 options. Either seeing if I can find or fabricate a simple flange to flange muffler delete pipe, or potentially cutting a stock muffler open, gutting it, and welding it back together. These may seem like half cooked ideas but 1. I love to weld and am pretty good at it, and 2. I am not in a financial position to be buying an exhaust, and 3. it seems that the stock pipe is a decent size on this truck. I guess my questions are as follows.

1. Has anyone done either of these?
2. How did it sound and run with a hollow muffler
- or -
3. Where did they source their muffler delete pipe?

I really appreciate the help as I am a relative newb to the ps/navistar/IH world.

[lcowner]

Don't bother gutting the stock muffler. Source the pipe from Summit or from a local muffler shop. They should be able to flair it for you too. You MIGHT be in to it for a hundo.

[lhsnbsaoa]

when i was looking to do this i could not fine pipe big enough at regular exhaust shops, you may have to check your local peterbilt or other tractor trailer repair shop. that is who installed my exhaust because the local "performance exhaust" wouldnt touch 4"...

[JJR]

Just go to Napa and get the Walker BTM muffler for 3.5" pipe. It is like $80 and is a flow thru design and works great. Just cut off the front pipe off muffler flush (the flanged pipe) turn it 180 degrees from original and weld in the walker.

[jesilvas]

I did the Walker BTM. Got it for about 63 at Advanced. Got it welded in for 65.

[KHaygood]

I cut out my old rusty stock 3" exhaust an am waiting for the last few pieces to arrive this week to put in a 4" stainless pipe -- downpipe for $104 shipped, 5' length of straight stainless on ebay for $80 (one end flared to go over downpipe), and a 90 degree turn to bring it out the side at the end of the cab.

I cut the stock downpipe off under the truck and it didn't really seem too loud without the resonator and muffler. If you need a muffler for inspection or sound reasons, getting something cheap like was recommended above sounds smart to put in the line, and easier than using the old one. But I've also seen straight pipes advertised that you just cram through the old muffler somehow.

A 4" pipe has nearly 80% greater cross sectional area than a 3" (about 12 sq.in. vs. 7 sq.in.), so it's got to flow better. I'm also gonna paint mine with ceramic.

While I'm at it, I'm hoping to get my old exhaust manifolds out, polish and port them as necessary, ceramic coat them and the up-pipes, and also put a new bearing kit in my turbo ($40 shipped from DHGate -- straight from Shanghai!).

I don't have the job done yet, so there may be something I regret in a week or so. Hopefully it'll all work right and make my 7.3 a little more efficient.

[jesilvas]

Stock is 3.5. Just sayin

[KHaygood]

Oh, interesting. Just measured -- stock downpipe is 3" but distal pipes after the resonator are 3.5", like you said. I just assumed they were the same. Thanks.

[jimmyp]

I cut the muffler out of my 2000 here about 3wks ago and used 3.5in flex pipe as a delete pipe, i did it just to see if i would want to listen to straights when I ordered my 4in. its not pretty but it works. ive got about $35 in 3ft of ppie and 2 clamps
Jim

[KHaygood]

Friends assume my stainless 4" pipes will be "pretty", but they don't realize you can't see any of it. They have no idea how grungy my truck is anyway. A little bit of shiny stainless will just enhance the contrast.