2006 V8 Exhaust manifold and cat converter

I have an '06 4.7 L V8, I have been using it as a secondary vehicle so I haven't given it the attention it deserves... I drove it for about 3 years with a faulty O2 sensor after a long road trip. I have had the leaky manifold for as long as I can remember with the annoying cold start click. I bought it used and never knew about the warranty repair until it was too late. Anyway, I digress, my leak has gotten bad and just this last week I started getting the rotten egg smell to which I suspect I have now gotten my cat converters involved. Took it to a shop and they wanted 5k for a full L/R manifold swap with new manifolds and gaskets. That's out of the question. Found an exhaust shop that is willing to do the labor of replacing with new parts I provide for $500. Question I have now is what parts do I buy?
I have seen threads about using DT headers instead, but I do need CC also so is that still the best option?
I have seen threads that OEM is best for CC but, if I replace the manifold with OEM I've seen many comments about why buy those if that's what cracks/leaks in the first place?
I have seen other comments about aftermarket CC only going to last a year or so. So, I feel like I may have shot myself in the foot by waiting so long to fix the manifold and O2 sensor that I let my CC go bad but, now looking for advice on how to proceed. Thanks!

 

Well, a couple things to consider about the OEM parts over the aftermarket parts. This doesn't include going to headers.

It's true that aftermarket replacement manifolds with cats are notorious for having the cats fail fairly quickly. They don't use the same catalytic materials that OEMs have access too, regardless of them being higher end, such as Magnaflow or not. However, they can be cheaper than OEM if that's a concern and there's no guarantee that they will fail. They very well could last several years without issue. It's just a gamble.

OEM are more expensive for sure but you also need to consider how long the original manifolds on your truck have lasted already. Most of them don't fail or get replaced until they are into the 200k mile + range. I didn't replace mine until over 300k miles. But when I replaced them, I went with OEM Toyota manifolds again because of my previous statements concerning how long they last and the catalytic materials used.

As to which parts should you buy, well, it's up to you. If you live in a communist state such as California, your only real option is to skip headers and go with either OEM or aftermarket replacements. There are headers that are CA legal but you still need to have a cat welded to the header to be legal and pass smog.

Hopefully that helps you some.

 

Thanks for the response. Nope, no CA here. Not will it be. Idaho/utah, it’s got some rust down there from salty roads. I’ve got 230 k miles and hoping to keep her running for as long as possible. But, trying to stay cost reasonable.

 

Just for informational purposes, how much are the manifold/cat combo for the v8’s (OEM). I’ve got 245k and live in California so I’m sure I’ll be due at some point.

 

I think I got mine for around $450 each from McGeorge Toyota online. Expensive, yes but they are OEM and my originals lasted me over 340k miles before they started giving me issues. Non- clearing O2 sensor CELs, even with brand new Denso sensors installed. New manifolds and there have been zero issues since with the same sensors. Don't forget to get new gaskets too! I used these Remflex manifold gaskets as they are thicker then OEM and will seal better:

https://www.amazon.com/Remflex-7012-Exhaust-Gasket-Toyota/dp/B00D3D9U2U

https://www.amazon.com/Remflex-7011-Exhaust-Gasket-Toyota/dp/B00EDFWUJW

***Correcting my link to the Remflex gaskets. Remflex 7012 are for V8s from 05 up with air injection. Remflex 7011 are for 03-04 engines without air injection. The 7012 WILL work on 03-04 as well.***

***Felpro 23626 are the donut gaskets that I used***

https://www.amazon.com/Fel-Pro-23626-Exhaust-Flange-Gasket/dp/B000C2G5WS

There's also the donut gasket after the cats that will need replaced, I have that part number on Google Sheets but that is blocked from work so I will post it when I get home tonight. You might also need to replace the manifold studs and nuts in the heads as they can and will rust over time and will either break or the threads will get boogered up when you try taking the nuts off.

 

Thanks @xtremewlr , don’t worry about digging into it, mine are fine (so far!) was just curious as to what to expect later on down the road.