I've got them installed. I've probably had them for 10 years or so. Did the job of reducing the smell but also made the exhaust quieter. My car never has been really loud, though. I ran 3 chamber flowmasters for years but now have Jones straight through. FRPP shorties, mac x-pipe, full exhaust to the back.

 

I've had hi-flow cats ever since I had the long tubes installed in the early '00s. I've never run without them, so I can't really provide any comparison on smell or anything.

 

I have thunderbolt spun metallic versions on my 89.
BBK long tubes, BBK x-pipe and Flowmaster Force II
Installed them on my off-road x-pipe for same reasons as you.
It may have quieted it down a little bit, but not a ton. I can say WOT in a tunnel is quite loud.

Short videos before and after idle and backing into garage.

 

I installed 2x Flowmaster 2.5" mini cats on my 95. Mac X pipe. Definitely cut the smell of fumes a lot but I'm very unhappy with the rotting egg/sulfur smell it has now when I get on it. The cats have maybe 500 miles I'm hoping it'll go away. Car did get a little quieter but still sounds great.

Had Magnaflow metallic mini cats on my H pipe they cut the smell significantly and no other odd odors. They were on the car when I bought it. Didn't feel like hacking up the H so tried to the Flowmaster units.

 

I installed 2x Flowmaster 2.5" mini cats on my 95. Mac X pipe. Definitely cut the smell of fumes a lot but I'm very unhappy with the rotting egg/sulfur smell it has now when I get on it. The cats have maybe 500 miles I'm hoping it'll go away. Car did get a little quieter but still sounds great.

Had Magnaflow metallic mini cats on my H pipe they cut the smell significantly and no other odd odors. They were on the car when I bought it. Didn't feel like hacking up the H so tried to the Flowmaster units.

Wonder if I could be confusing that smell for clutch

 

I added “high flow” cats to an off road X on my ‘90. The end result- it was a little quieter and it no longer smelled like gas pump. It didn’t feel any slower though.
On my ‘95 I removed the the front cats/resonators all together and the aft’s were replaced with “high flow’s.” The end result- it was louder but did not smell. These are on the ‘95. https://www.amazon.com/Universal-Catalytic-Converter-410225-Stainless/dp/B06ZZ35D3Y

 

With today's better tech, it's not a huge deal running good high flow ones. A terminator I just sold for a friend has virtually the exact same parts I do only had the magnaflow catted X vrs mine non catted one. Mine is louder for sure, but I kind of appreciated the 20% sound reduction. His car also made 650 on the dyno so it's not like it was getting choked out.

 

Right I know the converters are much better and only take about 5hp off dyno numbers. Just wanted see if peoples noses notice the difference lol

 

you won't notice the power just the benefits
(no smell and less attention from idiots and cops)

back in my na days and stock shortblock it was like 4rwhp and even less across the board

 

I'm running JBA ceramic shorty headers, Bassani catted X-pipe and Borla Pro XS mufflers. I actually have Flowmaster American Thunder on the car, but it think it will be too loud for my tastes so i'll be swapping to the Borlas in an attempt to quiet the car down.

The car is a street cruise with full interior and AC. I can live without 5HP by having cats if it will knock the smell and volume level down.

 

I'm running JBA ceramic shorty headers, Bassani catted X-pipe and Borla Pro XS mufflers. I actually have Flowmaster American Thunder on the car, but it think it will be too loud for my tastes so i'll be swapping to the Borlas in an attempt to quiet the car down.

The car is a street cruise with full interior and AC. I can live without 5HP by having cats if it will knock the smell and volume level down.

I don’t think you’ll even lose five. I had my dynoed after going from four oem cats to just two “high flows” and there was zero gain. It sounded better though.

 

I was also thinking about installing tail pipes on my mufflers to no longer make them dumps. The dumps don’t make thing any better

 

I run 2.5" high-flow cats after Accufab 1.75" mid-length headers into a BBK off-road x . Full exhaust through Flowmaster Fx straight through and over the axle. No fumes, but the Flows are way too loud for me.

 

I have almost the exact exhaust system as you. MAC equal length shorties, 2.5" ProChamber and I added 2.5" Magnaflow universal cats (to pass local emissions), 2.5" ProDumps with Flowmaster tails.

 

Sounds awesome

 

Do the high flow cats need fresh tubes installed? Interested in putting some on for the smell and sound reduction.


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Do the high flow cats need fresh tubes installed?

Mine have the tubes capped (not hooked up). My cats are located just behind the trans mount, before the ProChamber.

 

No tubes on mine.

 

What are these tubes we are talking about here? I am blanking in what that is referring to

 

Air tubes for the cats

 

Ah. Gotcha.

in that case, I did not install the tube. My air pump and all the plumbing is deleted.

if you look at the Bassani catted x-pipe (which is what I have) the air tube enters after the cats, so it’s useless

 

For those times you really want to make an effort... hahaha

 

I recently upgraded to BBK longtubes and cats behind my 331. Previously it had BBK shorties with an offroad x-pipe. It feels like it has a little more midrange, the exhaust is quieter and deeper, and most importantly the exhaust smell is much better

 

I need to install some cats to get rid of the smell and reduce noise if possible. Engine makes 475 RWHP or so with 2.5 inch exhaust. Whats a good, low profile unit to get? Those attached to the Bassani piece above look great.

 

Modern 3-way cats store enough o2 in the brick to where they don't need supplemental o2 for the reaction. In fact, if too much o2 is provided, they will burn up (which is why the Basani above has the air post-cats).

If you have a 2-way with air injection tubes and you don't run o2 from the pump? Then they can't do the reaction (they don't store o2) and will clog/burn up...

Have to know what you have to know how to set it up.

I run a pair of these. No smell, surprisingly quiet (vs non-catted, when i was aligning the system up) and will last a while. 49 state cats don't have enough material in them to last very long - which is why they are so cheap.

 

Thanks for the knowledge. My set up is long tube headers directly into a Dr. Gas non catted X pipe. Borla Pro XS mufflers. No smog pump. What else do you need to know? Those Walker units are pricey. What about something like this Magnaflow? MagnaFlow 53956 MagnaFlow Universal Spun Catalytic Converters | Summit Racing

 

Thanks for the knowledge. My set up is long tube headers directly into a Dr. Gas non catted X pipe. Borla Pro XS mufflers. No smog pump. What else do you need to know? Those Walker units are pricey. What about something like this Magnaflow? MagnaFlow 53956 MagnaFlow Universal Spun Catalytic Converters | Summit Racing

They are - when i got them they were $190/ea. The cost of palladium and other metals is through the roof right now, which is why used OEM cats are worth so much money right now (and theft is high).

It's just a supply/demand thing - plain and simple. It's also why the 49 state cats are cheap - they don't have any reactionary metals in them, and they become dormant pretty fast. Those walkers are CARB approved - which for our intents and purposes means they will last longer (the CA certification test is more stringent than the 49 state test - which is still far below the OEM EPA standard). So you can spend the money once, or you can spend it every few years when the 49 state cats go bad (or yearly if you drive your car a lot).

At this point, it's the cost to play the game. Overall, it's a few grand cheaper than an EPA fine if you get cited. That's where I stand at least.

 

Here is what I'm running. MagnaFlow 59956 MagnaFlow Universal Spun Catalytic Converters | Summit Racing If you're running under more severe conditions (racing, etc.) those ceramic honeycomb ones won't last near as long.

 

How would they know your 49-state cats are no longer functioning?

Here in my state (a very Cali-loving MA), converters are strictly a visual criteria. No actual sniffer test is done, and the hood isn't even allowed to be lifted. The inspector is happy, and at the rate I drive (100-200 miles per year) it's very possible that 49-state cats last me long enough to be useful anyway.

 

How would they know your 49-state cats are no longer functioning?

If you live in a state w/ a sniffer test, then you would fail due to non-function status. As far as visual goes, obviously with them there (even if low functioning), you'll prob pass. All I can say is know your local laws.

I'm in a 25yr rule state, so I'm free and clear. But I run them because I hate the stench - so for me, it was worth it to do it once/right. Hence why I went with a CARB EO certed cat. I've had the 49 state cats and they were good for less than 2yrs of regular driving. My time for replacement is worth more than the cost difference (49 state vs EO) as far as I'm concerned.

 

Ha. After a perusal of the Magnaflow CARB units, the Walker piece is a bargain. Im in NV and dont have to smog. Car is registered as a classic. Its mainly a track car (Auto X and Track Days) with street to and from at least locally. What happens to performance and smell (ability to reduce) when the 49 state units become low functioning? Im just after smell and sound reduction. Perhaps the 49 state units will still work for my needs?

 

If they don't function, then they don't reduce (chemical reaction) the stuff that stinks. A burnt out light bulb doesn't partially light up the room, you know?