What are the pro and cons on removing the cat and just adding a pipe on a 1985 iroc with the good cam TPI 305 and with all the other smog stuff taking off and on a 1979 trans am with olds 403 with no smog stuff.
THANKS

 

Pros= more flow=more HP, louder exhaust

Cons= bad for the environment, a hi-flo cat will hardly rob you of power, also if emissions are tough where you live that will be a problem.

 

No cons, all pros .

 

I second what Matt says. I was gonna run off road pipes on my 91 inplace of the cats but the smog officials here would put the cuffs onme real fast. it bad enough i took my smog pump off. i bought 2 SLP LS1 converters and had them welded into a custom setup. i havent had it inspected yet though

the louder the better

 

I'm with Mark on this one, and really the cons are really easy to get around.

 

all pros if you dont have to worry about emissions

 

Duke,

On your '79 TA, if you still have the large, old pellet type converter, get that piece of crap off there and install a mono-bed high flow cat converter, ASAP. You'll pick up flow like you wouldn't believe. Those old converters are a huge restriction, not to mention a friggin' boat aanchor.

And since you live in the area you do, plan on inspections within the next several years. They're coming soon to a neighborhood near you...

Once you do that, your '85 may take a few lessons from what you learn on the '79. Get the 3-way cat off the '85 and go with a high flow mono-bed there as well.

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For the rest of you doubters, remember that you're running NO cats the next time you get spanked by a stock Z06 Corvette. He's running FOUR cats and six O² sensors, and will eat you alive. Maybe you should consider ADDING cats insteaad of removing them, eh? Remember he's also got five less cubic inches to work with, so maybe eight cats would be a good idea on your bigger 350? You get the point, I hope. Good exhaust flow is essential, but that doesn't automatically mean that you can't get that flow with converters in place.

 

Well put Vader. I didn't realize the Z06 had that many cats.

 

Vader, don't the 405hp z06's get only 2 cats? I think that they were able to get rid of the pup cats with some sort of redesign. Good point about getting high flow cats though, even if your state dosen't have emissions testing now, who says they won't 5 yrs from now? I know Michigan used to (not now though hehehe), what's stopping them from reinstating it? Something to think about.

 

V6,

You could be right on the Z06. Since the pre-cats (pups) were so close to the heads, they actually did most of the conversion. The Powertrain guys may have gotten smarter in the last year or two, and been able to achieve a clean exhaust with just two again in a better location. Unfortunately, I don't get to look at too many Z06 cars. They're probably back to only four HO2S again, too. Still, you got the point. The high flow cats really don't restrict mush at all and can be tuned as an expansion chamber if properly sized.

 

my memory is a little fuzzy but if i remember the first year they had z06 they had four cats and 395 hp. I think they are down to two now and have 405 hp. My memory is fuzzy though

 

yes original 2001 Z06s had four cats and 385 hp. 2002s have 2 cats and sodium filled valves to get 405 hp. I don't know about sodium filled valves, but my 305 will run as fast as a new Z28!

Z06 is one amazing car, damn near as fast as a viper and with a whole lot fewer cubic inches. 346 vs. 488 (new viper is 506.5 cid). that thing should be faster than it is

:hail: chevy