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87 Mustang Gt 400hp Holley Terminator
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Discussion Starter #1
Kicking the idea around of putting cats on my exhaust system. Currently running Mac shorty headers, Mac H pipe with no cats, Mac dumps. In my opinion the holy grail of exhaust LOL. Butttt I’m sure tired of smelling like exhaust after a day of cruising lol. Who’s running them and what are your thoughts.
 

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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.
 

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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.

 

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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.

 

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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.
 

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2000 Mustang GT
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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
 

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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
 

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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.
 

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87 Mustang Gt 400hp Holley Terminator
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Discussion Starter #10
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
 

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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.
 

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87 Mustang Gt 400hp Holley Terminator
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Discussion Starter #12
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
 

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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.
 

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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.
 

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Kicking the idea around of putting cats on my exhaust system. Currently running Mac shorty headers, Mac H pipe with no cats, Mac dumps. In my opinion the holy grail of exhaust LOL. Butttt I’m sure tired of smelling like exhaust after a day of cruising lol. Who’s running them and what are your thoughts.
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.

Cats.jpg

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


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'90 Windveil Blue LX (Dart Turbo T56)
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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
 

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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.
 
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