Removing the cats?

chevy38fan · August 17, 2003

I've been thinking about doing this for about a month or so.

has anyone here done this with a 1996 tahoe with dual exhaust? if so how much louder is it, and did you gain anything in performance? did you get the rear O2 sensor simulators?

AZ1500 · August 17, 2003

Bad idea. More noise, you may get an ses light, you won't pass state emissions test and you'll be polluting the air. The gain, if any, in performance will be negligible. Headers and and a good catback system is all you need and you'll be legal. Make sure the parts have a C.A.R.B number.

chevy38fan · August 17, 2003

bah.. florida don't have state emissions test.

99Silver6.0 · August 17, 2003

I dont think that would be a good idea. That 350 needs some backpressure. I dont know exactlly good or bad it will run. But I dont think it would be a wise idea. Im not too familiar with the 96 Hoe's and how the O2's are set up. In front of and rear of the cat. If there is an O2 sensor behind the cat you will need a Sim. Otherwise that SES light will stare you in the face for all eternity! Just leave the cats be and get a good cat-back and some headers like AZ1500 said. That aught to make you some nice HP numbers.

woodrow · August 17, 2003

i have alot of friends with 350's. 1995 and up. but there all trucks

and stanard. but i have seen automatic also. they require no sensors

but they are loud with strait pipes. they have not harmed any of my friends

trucks so i would not worry about it

greyghost03 · August 17, 2003

You could always get hi-flow cats. Just another option.

496Cubes · August 17, 2003

I did this with my 91 camaro. I didn't have any issues. I've heard of later cars that if the O2 sensor wasn't working right the car ran like crap though. When they did mine they hollowed out the cat and put the straight pipe right through it. We don't have any emission tests here in Iowa, but a cop will take a look under your car to see if you have cats or a muffler.

chevy38fan · August 17, 2003

what exactly IS a catback system? and what's a good one. like my signature already says, I already have the original 40 series flowmaster mufflers.

The SPEEDY · August 17, 2003

what exactly IS a catback system? and what's a good one. like my signature already says, I already have the original 40 series flowmaster mufflers.

Catback is just a bolt up system that replaces the pipes and muffler from the cat back.

AZ1500 · August 17, 2003

Magnaflow

Check it out!!!

chevy38fan · August 18, 2003

well. there was a place around there that said they'd redo all my piping from the headers back and use my original mufflers (and gut the cats) for like 150 bucks. is that a good idea? so are the pipes from the cat back usually bigger?

CMNTMXR81 · August 18, 2003

If you decide to remove the cats and your truck being OBDII compliant, you will have to get O2 simulaters (O2 simms for short). These plug into the wiring harness where the factory post cat O2 sensor used to be and trick the PCM into thinking all is well and that the post cat sensors are adjusting the trims in accordance with the pre-cat O2's. This will keep you from getting an SES light. You can also remove your Secondary A.I.R. system if you remove the cats also as it will no longer be needed.

Other than that it's a noise and inspection issue.

chevy38fan · August 18, 2003

if I get one of them Westers PCM will I have to get those O2 simms? They're kinda expensive for as small as they are, lol

CMNTMXR81 · August 19, 2003

I am not familiar with the Wester's tuning.

The only time you need O2 Simms is if you physically remove ( or simply disconnect them from the wiring pigtail) the post cat O2 sensor(s) and cap the hole(s).

xtrapraise · November 14, 2003

On a stock vortec, you need adequate backpressure or your performance will significantly decrease.

My 98 K1500 RC SB 350 Manual trans 3.73 -has the normal bolt ons, and ive tried no cats (with Casper's o2 simulators), stock cats, and Random Technologies hi flow cats, all with a 50 series flowmaster dual inlet dual outlet with dual rear tailpipes.

No cats sound the best (and loudest), but my truck was a dog below 3500rpm.

Overall power was down and so was throttle-response.

The Random hi flow units worked the best, and were only slightly quieter than no cats. Performance with these was better than stock, and the sound was throatier, however, the SES light came on after about 20k.