Gutting passenger cats on 1996 corvette, any tips?

 

A SES light and code for low catalyst efficiency is likely. A long bar and a 48 oz hammer.

 

I had pipes welded in place of the cats of one of my '95's. It sounds great below 2500 or so, but like crap above that. I love the smell, but didn't care for the overall sound.

 

Thsi si the way to go. The hammer suggestion will work but it is a PITA and you run the risk of little pebbles of catalysis blowing through your system.

Cut and weld the pipe. Less than $100 and professionally done.

 

I did this on my 94' when I first got it. Hated it, ended up sourcing some gently used ones.

The cats really aren't robbing you of any performance or really any sound maybe a little. I didn't care for the stink, it sounded like a dump truck under part throttle, but did sound great when you put the hammer down. Leave it alone, the LT1/4 exhaust system is pretty well sorted from the factory. If you want different sound look into the eliminators or a catback that works within your budget.

 

Gutted cats on older cars usually helps a lot. On newer cars with lots of computers, it hurts performance unless you can reprogram or tune the computer. For the ls engines its easy to get a hand held programmer and select delete o2 sensor input. I don't know if 96 is that simple.

 

Why?

 

I've heard the complaints about the smell before, but, don't understand why it would. My 72 Z28 with a mild 350 had duals without cats and the exhaust did not stink. Why does it on our cars if we remove the cats?

 

On computer controlled cars the computer monitors up stream and downstream o2 sensors. If the cats are gutted the downstream reading will be different than what the computer is looking for and it will change the afr/timing to adjust and it wont be optimal. Older cars with just basic efi only have an upstream o2 sensor, so the computer isn't making as many changes to tuning.
My 93 Jeep got about 280-300 miles per tank with no cat. Now with cat its 230-250. So from 18-20 mpg down to 15-16. It is efi with only an updtream o2 sensor.

 

As mentioned, you can "gut" the cats or remove them. But your profile shows you live in CA; how are you going to pass smog? The '96 is an OBDII car, so you would need to program out the O2 sensors to avoid a constant SES light.

Going to a muffler shop to have them removed may not work. It is a violation of federal law to remove a working cat and if a shop gets caught doing so, they could be hit with a 5-figure fine. Hard to say what CA would do to a shop.

 

My personal experience with a 1996 OBII went something like this:

removed cat back exhaust in preparation of installing Corsa exhaust.

took flashlight and looked up into passenger side OEM catalytic converter; catalytic matrix looked fine;

took flashlight and looked up into the drivers side OEM catalytic converter, there was no catalytic matrix present, none. That cat had "self gutted".

At the time there were many 49 state legal catalytic converters available in the aftermarket, BUT NO ONE WOULD SHIP INTO CALIFORNIA and the only Catalytic converters available in California, .remember it is ILLEGAL TO RESELL A USED COVERTER IN CALIFORNIA, were the ones available new from the dealerships at..ARE YOU SITTING DOWN? $960.00 EACH.

Well that wasn't gonna work, so I finally was able to purchase a high performance cat out of state, have it shipped to an address in Las Vegas and then hand carry it into California.

Fortunately things have changed for the better, there are California approved direct fit cats now available at reasonable prices.

So yes, if your going to dedicate your Corvette to "off road use only and may never be used on a public highway" by all means , gut those cats, but don't expect a muffler shop to weld in catalytic converter eliminator pipes for you, those days are long, long, gone. And buy a pair of new, CARB approved direct fit catalytic converters for the times you wish to "drive on public highways".