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Old 02-02-2022, 10:00 AM
IA_TA IA_TA is offline
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Default Need exhaust help for 79 w/403

Need help finding an exhaust system with cats. I bought a 79 Trans Am. It will have a 403 that's just shy of 500 HP. It comes with long tube headers. I need to run cats because exhaust odors give me bad headaches anymore. Just a few seconds of smelling fumes from my previous C3 Vette would make me ill for some reason.

So, what cats and mufflers could I run that would perform well and sound good? Preferably without bad drone. Should I run an x-pipe? It'll be a toy for the wife and I to cruise iand take day trips in.
Here's the car I bought https://www.flickr.com/photos/restor...7720295603885/

I haven't owned a second gen for 25 years and I've always missed mine.

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Old 02-02-2022, 11:13 AM
78w72 78w72 is offline
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not sure of any pre made kits that include cats for these cars, best bet is to pick a kit you like in your budget & just add cats to it. pretty sure most companies like dynomax etc make a high flow cat. & im not for sure on this but do cats eliminate exhaust "odor"? always thought they were more for emissions of the bad things in exhaust... i know my modern cars with cats still stink pretty bad, its the tune of teh carb that makes the biggest difference in my experience, ive had cars that run very rich & will burn your eyes after just a short time of running in the garage with the big door open, can even leave small black spots under the exhaust tips on cold starts. so make sure the tune is spot on, maybe use an AFR meter & that should help the odors.

ive used the pypes kits & they fit very good, the X pipe is supposed to increase power but does tame the sound a little. i did buy a dynomax high flow cat for my old daily driver jeep that didnt need high flow but was a lot cheaper than buying an OEM one.

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Old 02-02-2022, 11:23 AM
IA_TA IA_TA is offline
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Thanks for the info @78w72. Cats definitely help with the fumes that bother me. When I was younger it was no big deal but now in my mid forties it's become a real problem for me. Sucks

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Old 02-02-2022, 11:53 AM
78w72 78w72 is offline
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happy to help. here is the walker brand i used, they make different in/out sizes. most other exhaust companies offer them too & the exhaust shop will put them in along with the kit you buy. the pypes kit can be DIY'd but a good shop was well worth the price for me since it needed minor cuts to fit best & i dont have a lift & didnt want to wrestle with it on my back.

they make some exhaust smell additives too if you want your exhaust to smell like cherry or grape!

https://www.summitracing.com/parts/w...SABEgJLhvD_BwE

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Old 02-24-2022, 12:19 AM
1965gp 1965gp is offline
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I have the Pypes crossflow muffler (transverse mount) with an x pipe on my 403 with long tubes and it’s way too quiet for my taste. I would get one with an H-pipe, that gives you more straight pipe to put cats in.

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Old 02-24-2022, 03:45 PM
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ZeGermanHam ZeGermanHam is offline
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I'm curious to hear what others have to say about this topic. I feel the same way - I don't like breathing exhaust fumes and I also don't like it when my clothes stink after a drive. I've wondered whether adding some high-flow cats would help in this regard.

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Old 05-21-2022, 07:34 AM
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BDH79TA BDH79TA is offline
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I realize this is an older thread, but Pypes makes a kit for the F-body that does have high flow cats installed just ahead of the X pipe. It's fairly pricey. I purchased the crossflow kit from them and just added high flow cats.

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Old 05-21-2022, 09:42 AM
78w72 78w72 is offline
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Quote:
Originally Posted by BDH79TA View Post
I realize this is an older thread, but Pypes makes a kit for the F-body that does have high flow cats installed just ahead of the X pipe. It's fairly pricey. I purchased the crossflow kit from them and just added high flow cats.
do you have a link for that kit? others may be interested.

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Old 05-21-2022, 10:02 AM
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BDH79TA BDH79TA is offline
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This is a link to that Pypes system. They've got a couple of versions of you go to their site and simply put in 1979 firebird.

https://pypesexhaust.com/i-23437343-...m-sgf940e.html

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Old 05-21-2022, 10:09 AM
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I purchased the SGF70 system for my 79 then added Flowmaster cats. Car is still undergoing resto so I can't tell you how it sounds yet.

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Old 05-21-2022, 10:20 AM
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I talk to my local Exhaust builder.

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Old 05-21-2022, 10:30 AM
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BDH79TA BDH79TA is offline
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Awesome. If you happen to live in an area where someone possesses the talent and equipment to do what you're needing, that's a good option. Unfortunately those can be difficult to find depending on your location.

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Old 05-23-2022, 04:26 PM
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napster napster is offline
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Gardener Exhaust makes an exact duplicate of the '79 w/ 403. The cost is $2,200 and the delivery is 24 weeks out. No cat in the kit.

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