Ive got a quick question. If I were to make a "test pipe" to eliminate the cat on a vehicle by taking 2 flanges and welding in a peice of pipe to replace the cat would it make a stock exhaust system sound bad or loud?? Thanks again! Matt

 

dont know about sounding bad or not, because tastes are differnt, but it will make it louder....

on a side note its illegal, but people always bash me when i say that, so do what you will, if you dotn care that its illegal, thats fine.....

 

Yes, it would make it louder. It will also kill your low-end tq. Back in my ricer days I put a test pipe on my Mazda truck and Civic SI. All it really did is spew toxic fumes into the air. Don't waste your time. Oh, and it's a federal offense.

 

Yes, it will make it louder.
It may also make those mountains you love become denuded hills.

 

Not worth the gains... and definitely not a good idea.
If you want loud upgrade the muffler, deckplate mod, ISR mod.

 

It seems like the more I read the more the backpressure theory seems like a wives tale. Everything I can find, REAL test shows gains from a less restrictive exhaust.

I removed 2 cats from my WRX and it was like a kick in the butt because the turbo could spool ALOT faster. BUT a turbo will make back pressure. So comparing this to my WRX is like apples to oranges...

I know all race cars have very short and very unrestrictive exhausts N/A and turbo. Of course the engines are alot different. So we are back to the apples and oranges again.

But back to the subject. Yes it will make it louder, removing the restriction of the cat. It made my WRX ALOT louder, loud enough I considered putting the one cat back on. I never did.

As far as power gains I would really like to see and independent dyno run on a N/A no cat vs. cat.

 

Louder, yes. But a loss of trq will be there, but a slight gain of hp may come.


I LOVED the sound of my 5.0 Mustang with off road h pipe and flows.

 

on a street driven truck its not going to help.... yes in a super modified environment, it will help performance, but then again your vehicle actually makes enough torque to compensate for the loss.... on a 4 cyl or a 6 cyl removing the cat will not net the same kinds of gains if any that you would see on a modified turbo or a large displacemnt engine that produces enough torque on its own... most smaller engines rev high and need to to produce the same numbers as a larger displacement engine...
diesels have huge torque numbers....they also make their power in the lower rpm range.. i drove a f550 powerstroke last monday that redlined at 3200 rpm.....

 

Instead of completly removing the cats just take them loose & run a piece of rebar through them & then put them back on. Make sure you shake everything out of them before you reinstall them.

Now I have a post in the forums about the exhaust pipes being restricted & if they need to be in order for good performance. No one answered on this site but this is a copy of thr reply I received from LC engineering tech support. I also ask them about installing headers & exhaust with no cats.

Let me start by saying that our header will not bolt up to a factory dual cat application. We have had customers install a header on that application and modify the exhaust from there back. The factory exhaust has a lot of back-pressure but you don't need all that pressure. The only down-side of losing back-pressure is losing a little bit of low-end torque but you will gain that back on the top-end.

THANK YOU

Jay Badaracco
Sales Department
Jay@LCEngineering

 

I'm very disappointed to see someone representing a well known company for aftermarket parts encourage illegal and unethical practices such as gutting a cat. I don't care if the argument is that "everyone else" does it.

That's a kind of logic that tries to shift attention from a lack of personal responsibility.



EDIT:

This part was rahh
This part was LCE
I misread the orginal post and was assuming the worst from LCE. I thought that it was originally Jay from LCE encouraging the gutting of the cat. However, I still am not impressed with the roundabout encouragement of going without a cat that was a part of rahh's interaction with Jay.

 

He did not say gut a cat. I did @ the top of the post.
He only referenced installing headers & opening up the exhaust.
rahh

 

I won't be purchasing or recommending anything from LCE anytime soon.

 

It looks like a direct quote from Jay at sales of LCE going by "rahh" here on YT. I've changed my post to reflect that misinterpretation.

 

OK, the cat question was not for my 3.0 Toyota, I actually replaced its cat with a new Toyota part when I installed my Borla exhaust. My cat issue was for my 1.6l Mazda, the previous owner had a very small universal cat welded in and the muffler blew out, one look at the 9 pieces of pipe all welded together under my car made me change out the entire system. I bought a solid used down pipe and an OBX racing stainless cat back with an inline resonator. Instead of a cat I figured I would try a real test pipe from an exhaust builder with 2 flanges and the correct angles bent into it. My theory was my car is a 1600cc engine, my VW was a 1600 and it had no cat and my ZRX was a 1200 with no cat.. why not try it. The issue is my exhaust system is just to barky and loud. I will buy a new cat and see if it makes a difference but I didn’t think they had an effect on noise. I also had no idea that it was illegal to remove them. I thought since not all legal vehicles have them that it was really up to the owner of the car if they wanted to run it. As for performance I can feel a noticeable difference in power and fuel economy with the current set up but its just way to loud.

 

Ilovemountains, your best bet is to snag a high-flow Magnaflow cat off ebay for $57 shipped. They work great. Lot's of vendors to choose from and shipping is fast.

 

jsut as a note, all legal vehicles must have a cat if it was originally equipped with one or if falls into the category that is built after a certain date.... if its older than 1974 it odenst require smog and doenst need a cat... everything else does..... not having a cat can actually make your car not be allowed to be registered....

 

In my opinion that is a waste of time yes it will make it sound louder but it is against the law

What i did to my old 2000 dodge dakota sport v-8 was i cut the muffler off and put back on a old pipe that was laying around it was cheap and it sounded throaty and it was loud on start up but it quieted down at an idle so u don't have to wrry to much on cops and it looks all stock it took me like an hour to two to do it but see my muffler had rusted so we just cut it off and it sounded really good
It was loud enough that my friend could tell when i was oming down his road which was about a mile or so away so it was loud

I hope this helps u out