Best way to accomplish this?

[Madbomber88]

Bought a 91 K5 that was modified to true dual exhaust from the headers back, with Dynaflow mufflers. System is in good shape but a little obnoxious for my taste

I’m in Virginia and my county has no emissions testing, but it failed inspection because the cats are missing.

So, should I buy two dummy cats and just weld them in upstream of the mufflers? Should I convert back to a single exhaust and one dummy cat? Or, should I actually buy a real cat or cats, even though there’s no need or testing that would be done requiring them? To pass, it just needs to look like cats or a cat is there.

I’d most likely go with Flowmaster 40 series.

 

[HankScorpio]

I ran dual aftermarket cats in Massachusetts. They were not very restrictive and just welded in. Similar situation as you. I registered at a high GVWR for a few years until I was exempt from the sniffer but visually the equipment needed to be there. This was back in the early 90's.

 

[Madbomber88]

I ran dual aftermarket cats in Massachusetts. They were not very restrictive and just welded in. Similar situation as you. I registered at a high GVWR for a few years until I was exempt from the sniffer but visually the equipment needed to be there. This was back in the early 90's.

Thank you! What part of MA? I was born and raised there and still call that home.

 

[HankScorpio]

Grew up in Bolton. Had a buddy with a service station in Clinton that played the emissions game for me.

Been a Wyoming resident since 1997....... but I will always be a Masshole.

 

[Madbomber88]

Ditto, proud to be a Masshole. I grew up in Princeton and was then stationed at Hanscom AFB for a while. I have some family in Bolton.

 

[dyeager535]

Bought a 91 K5 that was modified to true dual exhaust from the headers back, with Dynaflow mufflers. System is in good shape but a little obnoxious for my taste

I’m in Virginia and my county has no emissions testing, but it failed inspection because the cats are missing.

So, should I buy two dummy cats and just weld them in upstream of the mufflers? Should I convert back to a single exhaust and one dummy cat? Or, should I actually buy a real cat or cats, even though there’s no need or testing that would be done requiring them? To pass, it just needs to look like cats or a cat is there.

I’d most likely go with Flowmaster 40 series.

Personally, economically and physically, I believe single is the way to go. Single 3" typically is more than enough for your above average smallblock. I understand the aesthetics and sound argument of duals, that's individual preference. But for cost and ease of working under the truck, single generally wins.

This is single 3" off mid-length headers, into a Flowmaster noisemaker of some sort.
I think it's a 10.

Not into noise, that will be coming off for a Walker Quietflow. I have a name-brand aftermarket converter (Man, my memory stinks. Found it, Magnaflow) that I got for $100 off eBay that will be going on as well. My truck runs good, but under the right conditions exhausts still stinks and I'd like to minimize that.

Technically dual converters are not a thing on these trucks, but that's federal law, I don't think many states care that much. They only care whether it is or is not supposed to have converters, and if it does. They don't seem to care about how many lol.

 

[Blue85]

System is in good shape but a little obnoxious for my taste

I’d most likely go with Flowmaster 40 series.

If you add in 2 cats, it will get quieter and smell better. Can you work in a crossover pipe? But what is obnoxious about it that wouldn't be more obnoxious with 40's?

 

[Madbomber88]

If you add in 2 cats, it will get quieter and smell better. Can you work in a crossover pipe? But what is obnoxious about it that wouldn't be more obnoxious with 40's?

I may have to look again. I thought I had 40s on my old 90 K5 and it was pretty mellow and just a bit throaty when you stepped on it. But, looking at their site now. The 40s are on the aggressive end. My memory may be off!

 

[Wes Harden]

While I have no cats, I did have a single 3" no headers and a series 70 mufler. Sounded good no drone. Got it redone mufler shop put a series 50 on hate it.
Only thing about cats, are you maintaining the other emission controls ? Cats need precise fuel ratio management.

 

[1-ton]

My 1991 V3500 crew cab has a single 3" pipe exhaust with a high flow aftermarket CAT that does not cause much exhaust restriction. I have never been much of a fan of dual exhaust in square body 4X4 Chevys because you have to run the right side exhaust right next to the transfer case, which causes heat build up in the transfer case.

 

[Chickntrk]

70s trucks came with true dual exhaust

OP if I were redoing I would definitely go with single 3"