What are these? And why cant I find aftermarket headers with these?

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Calvo

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I drive a 1998 Chevy Tahoe 4D LT with the L31 350 (5.7). I'm looking to do a complete exhaust replacement, but the headers is where I'm finding most of my issues. I have these tubes that connect to the stock manifolds, I've included pictures below. There is a port in the front of the manifolds that are connected to each other and lead to this box toward the front driver side of the engine bay (pictures also included). No problem right? I don't have any issue with the car. However I CANNOT for the life of me find any after market headers that have this port/bung for what ever these things are. And thats the main issue, I don't know what the heck they are. If I didn't know any better I would just get rid of them, slap some headers on and forget about it. But then comes the issue of a warning light or car not starting due to the computer freaking out that I messed with something. Can any one tell me what these are, what they do, and wether or not I need them or not. I would like to do what I said and get rid of them if this is would be issue free, but in the case that this is WOULD cause an issue, Im seeking council. Please Only respond if you have answers Thank you all!

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(Passenger side manifold)
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(Driver side manifold)
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These three photos show where the tubing leads. I've highlighted in red, the tubes (partially silicon, but steel at the connection to the manifold) that connect to both manifolds and to the circular 'thing' near the front of the engine bay. Again please if you have any info let me know! If you don't have any info, don't respond unless you have something to add or you also have information.
 

df2x4

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AIR (Air Injection Reaction) pump system. Check the fourth post down on this page (from Schurkey).

https://www.gmt400.com/threads/air-pump.52176/page-2

If you disable it, you'll need a PCM tune to prevent a check engine light (and possibly other issues, not really familiar with this system).
 

b454rat

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Check out Hewett (not sure on spelling) but they do an AIR bypass kit. I had an 08 tundra that had it, they sell a kit that will bypass is without the check engine light coming on. Worked great on my truck.
 

Schurkey

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I'm seeing two separate systems.

The AIR system, in this case using an electric AIR pump off to the side of the engine; and also the supply tube for the EGR system--routing exhaust gas into the intake manifold.

One connection on the forward end of each exhaust manifold for the AIR system, one connection only on the driver's side exhaust manifold at the rear, for the EGR. Three exhaust manifold ports that ideally would also be on the headers.

God bless welders. Wouldn't be that hard to put those bosses into headers that don't have some or all of those ports.

Or just buy the shorties that have been linked-to in the post above.

My '88 has an AIR pump, I bought headers with AIR fittings. But I don't need the Vortec-style EGR tube.
 
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