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73-87 Chevy _ GMC Trucks => Performance => Exhaust => Topic started by: Dr_Snooz on June 20, 2024, 09:07:47 am

Title: Need advice - new exhaust
Post by: Dr_Snooz on June 20, 2024, 09:07:47 am
My entire exhaust system needs replacing. I have to pass CA smog when it's over, so yeah. I want to use these smog legal headers:

https://www.summitracing.com/parts/jba-1830s-4js (https://www.summitracing.com/parts/jba-1830s-4js)

This cat:

https://www.summitracing.com/parts/mpe-339109/make/chevrolet/model/v2500-suburban/year/1989 (https://www.summitracing.com/parts/mpe-339109/make/chevrolet/model/v2500-suburban/year/1989)

This muffler:

https://www.magnaflow.com/products/11229-magnaflow-4-x-9in-oval-straight-through-performance-exhaust-muffler-11229 (https://www.magnaflow.com/products/11229-magnaflow-4-x-9in-oval-straight-through-performance-exhaust-muffler-11229)

Stock routing, 2.5" -> 3", unless I can think of something better.

I'll also put in some V-band clamps to let me remove the Y-pipe for transmission work.

All advice is appreciated.
Title: Re: Need advice - new exhaust
Post by: ehjorten on June 20, 2024, 10:23:39 am
Do you not have the SMOG pump?

Sounds like you will either be doing some welding and fabrication, or you will be taking it to a custom exhaust shop.
Title: Re: Need advice - new exhaust
Post by: Dr_Snooz on June 20, 2024, 10:35:50 am
No smog pump. My nephew welds, so I'll be buying him something lovely and making with the nice nice.

 ;D
Title: Re: Need advice - new exhaust
Post by: Captkaos on June 20, 2024, 11:08:47 am
If you have the money I would get stainless piping if you have a welder for that..  and definitely use V-bands for disassembly.
Title: Re: Need advice - new exhaust
Post by: JohnnyPopper on June 20, 2024, 11:47:46 am
So your truck did not come with air injection? What year is it?
Title: Re: Need advice - new exhaust
Post by: Mike81K10 on June 20, 2024, 12:20:11 pm
When I first bought my truck (1981 K10 - Colorado Truck) it had a smog pump. Long removed!
Title: Re: Need advice - new exhaust
Post by: Dr_Snooz on June 20, 2024, 08:35:38 pm
It's an '89.
Title: Re: Need advice - new exhaust
Post by: bd on June 20, 2024, 09:41:49 pm
Generally, in California, you must maintain the original exhaust pipe diameter and quantity.  Cats must be specific by application per the pertaining CARB EO.
Title: Re: Need advice - new exhaust
Post by: Dr_Snooz on June 21, 2024, 09:07:43 am
Do you think there's a tech who will measure my exhaust diameter?
Title: Re: Need advice - new exhaust
Post by: bd on June 21, 2024, 11:12:39 am
They did on my 87 R10 w/TBI.  I suffered weeks long protracted arguments and had to produce a small book of documentation to "prove" that my truck was actually manufactured with a 3" exhaust, before the local CARB office issued an "exception."  All because the state's reference manual indicated the exhaust on my truck should be 2.5".  I won that argument but it was a trying PITA.  In other words, the risk is yours.  But that was years ago and times change.  Based on the direction California has chosen, it is probably worse, now.
Title: Re: Need advice - new exhaust
Post by: JohnnyPopper on June 21, 2024, 12:23:03 pm
Mike, nice to be free of your air pump!

Dr, if your rig came with one, per bd et al the CARB zantis will be looking for it!

Jus sayin... 8)
Title: Re: Need advice - new exhaust
Post by: Dr_Snooz on June 21, 2024, 09:11:05 pm
They did on my 87 R10 w/TBI. 

I kinda feel like there's more to this story, lol. Anyway, my install is legit. Everything is stock. Everything has an EO number on it. My shop knows that everything I bring them is legit. It may look shabby. It may have quarter million miles, but it always blows clean.