Need help with doing V8 exhaust from manifolds back!

[Dustin1]

Hey all, really could use some help and pointers with what to do with our 4R's exhaust. We've had the truck for 4, going on 5 years. I've been putting off addressing the exhaust manifolds for years now. Now the cats are throwing P0430 codes and the y-pipe is rusted out with a 0.25" leak all around. Needless to say, I'm thinking about just doing the whole exhaust, manifolds all the way back but the prices of everything is making me ill. Looks like Doug Thorley have been out of stock for over a year (I've been on/off watching them). I'm not sure what to do at this point. I'm ok with a little growl BUT I work night shift 1430-0300 so I have to be mindful and courteous of my neighbors and neighborhood. This is what I'm considering doing: standard exhaust manifolds w/ cat assembly > *DELETE* the second cats > new y-pipe > reuse my current resonator and keep it in same location (maybe delete depending on feedback from y'all) > *DELETE* muffler.
Things to note: my state does not monitor exhaust emissions. OBD checks only. I have an auto-mechanic friend that I'm paying to do all work.
Need help on what headers or exhaust manifold/primary cats assemblies to go with. Any other tips on what to do for build or what brands/parts you all can recommend? Looking to start project in late March when it warms up.
Thank you all!

 

[JONBOY345]

Check out my signature for parts I used, and look through my post history for pictures.

I will strongly recommend not deleting your muffler if you want to be courteous to your neighbors.

Best advice I can give RE: DT, get them ordered ASAP. The Sooner you order, the higher up the build sheet you'll be.

 

[Bassturd]

I’m about to do my drivers side manifold while I’ve got the transmission and T-case down for the rear main. I’m not going to do headers but just replace the manifold with a stock one and hope it lasts awhile. I have an 04 V8 here’s what I have for a parts list so far. Hopefully it helps you.

 

[ghabe]

Check out my signature for parts I used, and look through my post history for pictures.

I will strongly recommend not deleting your muffler if you want to be courteous to your neighbors.

Best advice I can give RE: DT, get them ordered ASAP. The Sooner you order, the higher up the build sheet you'll be.

Why did you pick the long tube headers instead of the short tubes? I was thinking of getting the short tubes and welding cats direrctly to them, either my original ones or the GSports.

Also, you still don't have any check engine light or codes? If not, did you use any special trick to prevent them? (O2 sensor simulator or spacer)

For those curious to see JONBOY345's setup:

https://www.toyota-4runner.org/3679983-post7.html

 

[JONBOY345]

Why did you pick the long tube headers instead of the short tubes? I was thinking of getting the short tubes and welding cats direrctly to them, either my original ones or the GSports.

Also, you still don't have any check engine light or codes? If not, did you use any special trick to prevent them? (O2 sensor simulator or spacer)

For those curious to see JONBOY345's setup:

https://www.toyota-4runner.org/3679983-post7.html

So that's a long story, but in short, I had the shorties initially, but the fabricator my mechanic used wasn't the best, and the alignment of the cats was all outta whack. He made it right by not charging me for his fabricators time, but it would cook the grease out of the slip yoke on my front driveshaft pretty quickly, and I just wanted the peace of mind that it was done correctly.

So, I moved to the Long tubes because I could do the work of removing the shorties, and old modified y-pipe, and installing the LTs in the driveway myself. All that was left was to find a fabricator to clean up the gesi cats and weld those in place of the DT resonators with some new O2 bungs downstream of the cats.

And no codes and no tricks. The downstream O2 bung was installed so I could reinstall the downstream O2 sensor and have it function as intended.

You could do Shorties + the Gesi cats and whatever y-pipe you want but strongly encourage your fabricator to make a jig from the OEM manifolds so they don't have the same issues I did.