Put on high-flow cats. It's annoying following a car without cats, especially one with a larger engine like a 5.0 liter. Yes, it stinks. My high-flow cats have passed emissions 5 years in a row now...

Dan
'91 928GT S/C 475hp/460lb.ft

 

Hi-flo cats are the best. I noticed a bit sharper exhaust smell after converting but it's very mild and actually I kind of like it. Not obnoxious or hurts the senses like those who don't run cats.

However, if your engine is at PEAK shape, then you can pass without cats.

 

do it !

 

Why does it smell so bad? Most cars ran without cats years ago and I don't recall any funny smell.

 

because your gas has no catalyst.

totally normal.

 

Speaking of fuel smell.... I've heard of some people adding a spark plug system to ignite the extra fumes and plow some small flames from the exhaust. Has anyone done that and does that actually work?

 

That's when it was normal.

You didn't notice because they were all like that.

I do recall winter mornings with dad warming up the car in the garage with door open, and still choking on the result. On only a 3 yr old car. Before cats. Ugh.

 

I had an employee who ran his Honda Civic without cats. It was an old model and wasn't supped up or anything, think he did it for gas mileage or something...he was putting up 45mpg, but the smell was awful.

If we were the last to leave, I'd try to get out first so I don't have to drive behind on the way out. That or I'd keep a 500ft gap since it was tearing me up.

 

I run original cats.

Harvested a set from Jadz 928's Perl white car for use on an 84 Euro.

Harvested a set from a wrecked 86.5 for future use.

The originals are good ones.

If I need a lot more power, I'll add a newer Vette to the portfolio.

 

Since it's so easy to get performance while keeping the cats, I'm not seeing any reason to remove them. Got a stock engine and mostly-stock rest of the system? The only performance you'll appreciate is the iincreased sound pressure levels that seem faster.

Meanwhile, especially for the rest of us that do actually inhale once in a while, cats are friends to all of us. Smog components don't magically disappear, they just get diluted in surrounding air. It's still contamination. I'm not a tree-hugger or any kind of rabid smog ****, but when there's no significant advantage and a well-defined downside to removal, why do it?

And for those who believe the myth that their car can easily pass smog with no cats, I challenge you to take your car, in its current tune and with no changes, and pass Cali smog with samples taken before the cats. I have no reason to believe that California standards are any tougher than other smog-checking states. Give it a try if you truly believe it will pass, and post the results for the group. Mine, with stock everything and with brand new ignition components and oxy sensor, won't pass without the cats.

 

getting the old very brown 1980 to pass it needed the cat and a new O2 sensor and just barely made it but pass it did !!

 

Well, my car does have that "vintage exhaust note" so I assume that he cats are shot.... anyway, thanks for the insight!

 

cars with cats smell funny. have smelled funny since 1974.

 

I went with an X pipe and muffler bypass. I don't smell anything strange...but then again I don't sit in my garage with the engine running without the door open.
The car sounds great. I get tons of compliments and yes it's loud but I like it.

 

An X-pipe and rear muffler bypass leaves the cats in place. The changes you made should change the sound (and available horse power), but should do little if anything to the car's emissions.