Removing the Cats..

Rage91GT

New Member
Sep 22, 2011
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I am looking to remove my cats and pre cats and run long tubes to an H pipe and flow masters.. Now my Question is what do I do with the wires plugged into the stock cats that has something to do with the smog system that is on the car.. Suggestions please.. Also how much horse power do you think you can free up with just removing the cat's
 
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The "wires plugged into the stock cats" are O2 sensors. You're going to need those for your car to run properly. Most, if not all, long tube headers are going to have accomodation for you to install them on your new parts. As far as how much of a gain, it depends on what else has been done. On an otherwise stock engine, probably 10-15 hp.
 
Long tubes, no cats and flowmasters on a stock engine will sound like sheet. You might want to put that money into the engine to make some power first.
 
Bwahaha I needed a good laugh this morning. Short of a new cam engine mods aren't going to change Jack.
If that's the exhaust you want roll with it.
 
If your cats are plugged, get new cats.

Otherwise, in REALITY, depending on MANY things, you can LOOSE HP. If FACT, if your cats are not clogged, you WILL LOOSE low-end HP.

On SN95s, removing the cats are often a guarantee loss of power across the band.

FWIW, a stock, or NA engine, will LOOSE HP ACROSS ALL OF THE RPM RANGE with no headers or cats (heads open to the atmosphere).

There have been many articles on WHY BACK PRESSURE IS NEEDED IN REAL LIFE for NA engines!

There's a book on Dyno numbers and the 5.0. Instead of wasting your time and money on RICER mods, spend ~$20, learn to read, and do mods that make sense for HP. Also note that many of those tests in the book are NOT done on new cats.

After ~50K-<75K miles, you SHOULD REPLACE THE CATS on a 5.0 because the 5.0 is such a non-clean engine. Still, unless the engine ran like pure **** because of a failure, you're NOT looking at big HP gains compared.

For HP, a new BBK X-pipe with cats is likely better than a non-cat pipe for any engine that's producing less than ~500HP.

Note: The above is about HP, power across the band, power under the curve, etc. It's NOT about how it "sounds" verses an exhaust with cats.


Gotta go and adjust my TPS now.
Hmm, 0.9999999v gets me ~60,000HP, gas mileage above 5,000,000,000 MPG, and I run the quarter mile faster than the speed of light!
REALLY!!!!
Just ask at any local RicersRUs meet. :)
 
Take stang&2Birds advice. It is some of the best you will get.

Removing the pollution control equipment from a 5.0 Mustang is a bad idea. All you have accomplished is to make the computer mad and spit codes. The pollution control equipment all shuts off at wide open throttle, so the HP losses from it on the car are 2-5 HP. The catalytic converters may soak a few more HP than that. None of the pollution control equipment reduces the HP enough to cost you a race in anything but professional drag strip competition. I seriously doubt that you will be in the final runoff on “Pinks”, so leave the smog equipment in place and make sure it is working correctly.

Know what does what before removing it. Remove or disable the wrong thing and the computer sets the check engine light and runs in "limp mode". Limp mode means reduced power and fuel economy.

Here's a book that will get you started with how the Ford electronic engine control or "computer" works.

Ford Fuel Injection & Electronic Engine Control 1988-1993 by James Probst :ISBN 0-8376-0301-3.

It's about $20 from Borders.com see http://www.amazon.com/ . Select boo...e to check cars, but it is still Federal law.
 
Long tubes, no cats and flowmasters on a stock engine will sound like sheet. You might want to put that money into the engine to make some power first.

I disagree completely. That's probably the ultimate "muscle" combination your average Mustanger is looking for. The only think that could make it sound any better would be a little cam lump.

On a side note...the highway drone would be unbearable for most, but if you're immune to it, have at it.
 
I disagree completely. That's probably the ultimate "muscle" combination your average Mustanger is looking for. The only think that could make it sound any better would be a little cam lump.

On a side note...the highway drone would be unbearable for most, but if you're immune to it, have at it.
I agree that I do like the sound of an x-pipe without cats on a 5.0. But, note what I say at the end. :)

Also many States/areas, they have noise pollution laws. And, the increased sound will not be legal. Also, it's a violation of Federal Law to remove pollution control equipment.

So, if someone doesn't have to pass smog, doesn't have to worry about noise laws, and doesn't drive the car much (we are talking about 20+ year old cars :)), and someone wants the sound of an exhaust without cats, then I see it as personal choice.

Still as I said, do NOT remove the cats to "gain HP". Unless it's a quarter mile track car, the LOSS of lower RPM torque and HP will NOT make the car faster or help it get better gas mileage.


FWIW: I have both. In fact, I have all "Four"! :)
1) BBK X-pipe with cats.
2) BBK X-pipe without cats.
3) BBK H-pipe with cats,
4) BBK H-pipe without cats.

BBK often has very good deals on returns. Just gotta keep checking. I've been checking for the past 10+ years. So, don't expect to find the deal you're looking for in a short time. And yes, IMHO, I like the BBK stuff much better than most of the cr*p out there.

For me, I like sound the BBK X-pipe with cats the best. :nice:
 
I agree that I do like the sound of an x-pipe without cats on a 5.0. But, note what I say at the end. :)

Also many States/areas, they have noise pollution laws. And, the increased sound will not be legal. Also, it's a violation of Federal Law to remove pollution control equipment.

So, if someone doesn't have to pass smog, doesn't have to worry about noise laws, and doesn't drive the car much (we are talking about 20+ year old cars), and someone wants the sound of an exhaust without cats, then I see it as personal choice.

Still as I said, do NOT remove the cats to "gain HP". Unless it's a quarter mile track car, the LOSS of lower RPM torque and HP will NOT make the car faster or help it get better gas mileage.


FWIW: I have both. In fact, I have all "Four"! :)
1) BBK X-pipe with cats.
2) BBK X-pipe without cats.
3) BBK H-pipe with cats,
4) BBK H-pipe without cats.

BBK often has very good deals on returns. Just gotta keep checking. I've been checking for the past 10+ years. So, don't expect to find the deal you;re looking for in a short time.

For me, I like sound the BBK X-pipe with cats the best. :nice:

While I agree with you with removing the stock catted H-pipe costing some Mustangs a little in the torque/horsepower department at many areas of the power band, this rule of thumb pertains more to later model Mustangs and the Fox body is most certainly an exception to the rule.

Adding an off road H/X-pipe to an otherwise stock 5.0L has show improvements across the board in countless dyno comparisons over the years. More so when combined with the rest of the exhaust system. While there may be the slightest penalty in the lower off idle regions of the power band, the gains made beyond that far outweigh the losses down low.

That being said....I would always recommend going with a high flow catted mid pipe as a replacement. Modern cats don't rob the horsepower that the older cats (like the ones our Fox bodies were originally adorned with) do. The horsepower and torque losses in many cases are negligible in all the but most extreme horsepower building situations.

My post earlier was based strictly on the audible tone a system like this provides, as the poster I quoted made remarks based strictly on sound quality. If I had the choice, I too would outfit the vehicle with a high flow catted mid pipe over an off road design as well. Partially because I can’t stand the smell of exhaust fumes in any of my drivers, but also catted mid-pipes do a better job of quelling the dreaded exhaust drone associated with aftermarket exhaust systems…which I hate even more than a stinky exhaust.