So I just finished a lot of work on my car and I think I am close to it running great, sounding quiet, and maybe not needing anything major for a little while. Well, at least I can dream.

I have an exhaust leak. Probably more than one from the sound of it. A few years back, I replaced one of the CAT assemblies. I think it ended up being around $1400 to do. I forget which and when I was under it a while back, they both looked almost the same even though one is like a decade older than the other. Those things age (rust) fast.

I was talking to my boss. He has a Mustang. He said that he redid his exhaust a while back and did just pipes and mufflers. No CATs. He is in Missouri where they do emissions testing and I asked about that and he said that he always passes. I am in Illinois and they do not do emissions testing. So I am curious if I could just do a similar system without the CATs and what you would recommend if I go that route.

 

Most states require a visual inspection and confirmation that your car is equipped with catalytic converters. Research Illinois, or find yourself a shop that does this with a wink & nod.

Without any catalyst, your exhaust will have a rotten-egg smell (sulfur dioxide). Some people don't notice it, and some simply can't live with it.

Without converters on the G, you will have a heavy rasp in your exhaust note. Some people don't care, and some lose their minds.

Your car, your call.

 

Thanks. I have lived here over 12 years now and had many cars between myself and my wife. Some new, some used, some dealer bought, some privately bought. And we have never had to get any type of an inspection for anything. It took a bit of getting used to coming from states that always did. I just registered my Tundra a few weeks ago and all they wanted to see was the old title, bill of sale, and insurance. That was it.

I was not aware of the smell. I have had older cars without CATs and never noticed this. Is it because of something with the newer vehicles?

I thought the mufflers would be what shaped the sound. Hmmm...now I want to know what it sounds like before I do it. Chicken and egg.

Edit: I did some reading and it looks like I am just lucky because I am not in any of these counties...

"Additionally, vehicles are subject to mandatory smog checks for residents of the following counties."

• Cook
• Dupage
• Lake
• Kane
• Kendall
• McHenry
• Will
• Madison
• Monroe
• St. Clair

 

Between the rasp and smell it's not worth it. I would go with a high flow cat, they are a fraction of the price.

 

Some companies make a resonated test pipe. That would tamp down the rasp.

As for smell... for the most part, that's behind you.

 

Ok..you just hit the nail on the head. I am trying to lower the cost. My car is a 2009 and pushing 220k. It still runs great but I don't really want to sink a lot of money into it. So if there are legal options that are cheaper than going with the "standard" cats, then that is what I am looking for. And I am leery of the no-name cats that I have seen on eBay. So I am looking for a cheaper option that is also proven reliable. I will take a look at what I can find for high flow cats. If you can recommend something, I'd appreciate it. My hope was to find a solution for around 1k installed. Only hoping for that because my boss said that is what it cost for him on his mustang.

 

This is what I have on my car, but there are a ton of other options for HFC.
https://www.z1motorsports.com/test-p...ts-p-4204.html

I got mine open box for $300 on the forum here, you can check around for good deals.

 

Thanks! I will look around some more, but those look like a great alternative to OEM and I like the price!

 

So I did some reading today, and my head hurts, but I think I know a lot more about exhaust systems than I did yesterday.

I am looking at the Kinetix HFCs That iCrap mentioned above and also the resonated ones by Fast Intentions. They are significantly more, but I am wondering if I would be happier with them.

One concern is that I ran across a comment where someone said that having the resonators that close to the header makes them prone to breaking apart due to heat, that they are not designed for that kind of heat. I am curious what others would say to that. It is definitely making me lean towards the Kinetix. I also have an email out to Fast Intentions asking them about that potential issue.

I am also looking at a couple of cat-back systems. One is made by Invidia and the other is made by Manzo. I have read a few good things about the Invidia here on the forum. The Manzo is almost half the cost, but I have not read anything about it. Anyone here have any experience with Manzo? https://manzousa.com/product/infinit...xhaust-system/

 

FWIW I bought these Kinetix HFC in March of 2021, replacing rattling OEM passenger cat. I sold my oem cats for 250 or so, paid 429.00 shipped from Redline for these. Love them, they are holding up well and no rasp

 

Hey Arthur, as much as it's going to hurt to do all of this research it will pay in the long run.

Most of the times folks enter the full exhaust world guided by looks and videos they usually end up in rasp.

The deleting the cats will open this door regardless of what anyone says. The fight then becomes pairing the right resonators and mufflers to combat this rasp which frustrates folks and have them throw even more money at the car trying to tame this down.

High flow cats are the in between of these worlds. HFCs are the way to go here.

After this my best recommendation is to replace piece by piece as you go. Exhaust components go through a type of "break in" process which all it really is is material wear. Once these components see about 1k of driving or so you can expect this sound for some time.

With this being said you'd be surprised on how HFCs and a Y pipe can improve in sound at times rendering the need to keep going worthless other than to obtain more power, increases in the rest will increase sound.

Unpopular factual opinion: More sound = more power regardless of what folks think.

Sucks however off tune trumpets are far more annoying.

Lastly don't be afraid of your local muffler shop as well, once you install HFCs take a trip and see how much a Y pipe and 2 bigger resonators would be, start from there and see if you like the sound, then lastly end it with mufflers (see through mufflers are more resonators than mufflers, find something with a decent canister)

 

I live in illinois as well. They do emissions testing here. They do not do a visual inspection but rather hook up a computer to test if all your monitors are ready. If so, theyll pass you. Ive seen people pass without cats but its a 50/50. If you do end up taking them off I will buy them.