Built my own T304 SS catback

Decided to build my own since there aren't too many 304 options out there in my budget. The muffler is a Dynomax 17289 ultraflo muffler. 2.5" 16 gauge pipes. I found an exhaust flange that closely resembled the oem flange. I did have to elongate the mounting holes for the bolts to fit back in.

The oem hangers are 1/2", not 3/8" that i was told.

 

I’ll buy one

 

This really makes me want to go buy a tig

 

Nicely done!

 

Lol. Thanks. I'm not really great at welding, so I'd hesitate selling it.

Welding is fun!

Thanks! The most time consuming part was figuring out how to get the exhaust hangers placed and where to weld them.

 

Nice work! Where'd you source the 304 (the pipe, the hangers, and the flange)? Would love a sound clip with the Dynomax, too.

Thanks!

 

All ebay. I found a set that they expanded one side for slip fit joints which made the whole thing much easier to weld since I didn't need to back purge the pipes. I used solar flux on the pipe to flange weld, but that was it. You could actually build the entire system with clamps with only welding needed for the hangers and flange. I actually made it in 3 sections. The pipes slip inside the muffler, so I used clamps on there. The hangers I got were straight, so I had to cut them and weld to 90 degrees. Even if I had bought 90 degree bent hangers, I still would have needed to cut most of them.

Flange: https://www.ebay.com/itm/153611699579

Exhaust hangers: https://www.ebay.com/itm/113824409912

Pipes: I bought 2 of these kits, but ended up also buying a 4' straight section for less welding in front of the muffler. In total, I used 2 90 deg bends, 2 45 deg bends, 1x 4' straight, and1 straight slip fit because it was much easier welding the hanger to it and putting it on the long section to mark it before welding.
https://www.ebay.com/itm/193217787640

The tip is a Dynomax 36473. I bought it from Amazon because of the price, but it looks like they raised prices since then.

Clamps: https://www.ebay.com/itm/283615147139

 

dynomax says their muffler is 304ss which is partially true. I believe the perforated pipe itself is mild steel. I ran a magnet over every single part I got in and it stuck really strongly to the pipe. The body itself is 304. I ended up painting the exterior part of the pipe with engine enamel since I wasn't going to weld on it.

 

Great info, too. Thanks.

Walker had a 304SS intermediate pipe with flange and o2 bung available for 1st gens. I got one and built a cat back for my 2000 truck. Can't find that for my DCLB 2nd gen, so looks like I'll have to copy your method. I've always liked Dynomax exhausts on Toyotas so might copy you there, too. Here's the sound clip I found of the Ultra Flo on a 4.0L Tacoma. Sounds perfect to me (no drone, rasp, etc)

https://www.youtube.com/watch?v=eLu1LiwpY_8

 

For cost comparison what did it cost to build parts cost, labor time? Looks good.

 

I just did a short run. The mic doesn't really pick up how loud the muffler is. Sound is almost not there at cruising speed. It's much louder at lower speeds (between 0-40).

https://youtu.be/mwUnnr5YS7M

 

At my calculation, I was at $375 on parts, not including supplies such as 308L filler rod for the tig, an argon refill, solar flux, etc. Knowing what I know now, I could probably do it for less since I know which pipes I need. However, I got the muffler for $100 shipped. Which is far less than normal.

The tip seems to rotate down after some vibrations, so I'm going to look at it today and see what I need to do to keep that from happening. Most likely, I will install a new exhaust hanger somewhere.

 

I know nothing about welding, but if the rest of the exhaust isn't twisting or turning and causing it to interfere w/ anything, why not just put a little tack weld on the exhaust tip? Make it a not-so-clamp-on
Regardless of how you decide to solve the problem, very nice work on building something yourself. You should be proud.

 

Any performance increases?

 

Thanks for the kind words.
The tip itself is not the problem. The entire pipe rear of the muffler is making a slight turn. Most likely because I should have welded on the rear hanger slightly lower than I did. Rather than cutting it off and making a mess, I'll probably find another place to install a new insulator and hanger. The hangers I ordered came in a pack of 10, so I have some to spare. There might be other options That I can come up with as well. I'm toying with the idea of an exhaust clamp with a threaded rod welded to it where I can rotate it and lock it with a nut. Something similar to a tie rod.

Probably not a lot. No idea if it's a placebo effect but it feels stronger down low.

 

Well, I took another look at it today and was able to tighten the rear clamp even more. That seems to have tightened up the rear pipe. Hopefully, it stays that way. I'll let it go for a couple weeks to see if it changes.