lspower

first of all love the place
i am a new guy looking for an answer , i have just bought a 90 ls400 and removed the 2 middle mufflers, i was wandering if i cleaned out the 2 cats if the engine run ok? i know it will be breathing much better but, would any check engine lights or any other problems come out of this.

thank you
ryan

Pagong

check with your state law if its okay to remove the cats. here in washington if you get pulled over and the cops so happens to look under and find out that there are no cats the car will be towed and you will be stamped with a hefty fine.

And you might not pass the sniffer test without the cats...try getting two high flow cats instead of getting rid of the stock ones altogether.

lspower

im ok on the sniffer tests, and i would just clean them out and put them back on (so they are there just nothing in them), but i was more worried if any check engine lights came on? or if something would go haywire on the car

thanks in advance

Pagong

as long as you have both 02 sensors connected you should be okay.

lspower

has anyone tried this and are you sure the engine would run fine w/o any service lights?
thanks

Pagong

you're check engine lights will NOT turn on if you remove your cats, the reason being is that only the 02 sensors are connected to the ECU not the cats. You can even look under your car and locate your cats and see if there are any wires connected to it.

Check Celsior Masters post on his new exhaust setup.

JBrady

You should be fine on a pre-OBD vehicle. The O2 sensors are before the cats.

Now, I do NOT advise gutting the cats. Problem is you create a large empty volume right after the manifolds and that kills velocity and induces turbulence. It also creates a sounding board that is loud and drone-eey.

If you MUST remove your cats... the proper way is to replace them with straight tubing. If you want to get fancy you can gut the cat housing AND weld a straight piece INSIDE the housing to create the look of a cat without the problems of a gutted cat. I advise getting a second set of used cats for this project so that you can use the flanges for a factory fit and this also leaves your existing cats available to reinstall if you need to including if you decide to sell the car.

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Jasoneo5

iTrader: (4)

Where did you get the pipes that are now in place of where the cats used to be?

lspower

thanks for all the help and info, and one last quick question?
if i do just gut the cats will i gain horsepower or loose it b/c of the
"Problem is you create a large empty volume right after the manifolds and that kills velocity and induces turbulence" ?

thanks

Jasoneo5

iTrader: (4)

What is inside of the cats? How would you "gut" it? I would also like to know about the gain/loose horsepower on that one too. This would make my Lex a bit louder also, right? Thanks for all of your help!

-Jason

Pagong

"What is inside of the cats?"

the cats have a bunch of mesh screens inside it...when i say a bunch i mean a bunch.


"How would you "gut" it?"

Last time I gutted the cat on my Honda, i just punched it with a very long screw driver. then cement like stuff will pour out of the cat then eventually when you punch through the screens the screens itself will fall out.

About loosing the HP, not really sure...JBrady can probably tell you about that one.

Louder? not really since you still have the mufflers in place.