Ok. I know that NC is less strict than CA (isn't every state? ). I'm trying to search for HC numbers from other failed people's cars so I can get an idea if something is REALLY wrong or if it's just the punched cat (cause my number is REALLY huge and that worries me that something else is wrong).

Again, Mahjik, thanks for your input. You're helping me out a great deal here and I really do appreciate it.

 

Don't go for longevity - after 1/1/06, pre-OBDII cars in NC only have to pass visual/safety inspection (no sniffer).

 

The stock cat has 2 1/2" piping. However, the flanges that are welded to the inlet and outlet, are welded on the inside. This reduces the opening and exit diameter of the cat to about 2 1/8". That is a 27% reduction in both openings, and is a significant restriction.

There is a simple and inexpensive mod for this. Remove your cat, and re-weld the flanges on the outside. Any decent welder should be able to do this quickly, and inexpensively. My neighbor welded them for me, so all it cost me was a few beers After the flanges are welded on the outside, you can grind down the inside welds to a nice smooth finish. It is important that you weld the outside first!! You don't want it coming apart.

I did this on my car, and was able to feel a small increase in power. Definitely worth the time spent. Now I have a "higher flowing", smog legal stock cat

 

ive got a metalit cat (but i havent put many miles on it yet... maybe like 6000 mi?). anyway i really like the cat, but the price was a little steep. IIRC, that was the cat i was running when i passed my last CA ****-smog test. the cat warms up in about 15-20 seconds it seems.... and if i stick my nose up to the exhaust all i can smell is hot air. it also seems to flow pretty well... and i ended up porting my WG to prevent any boost creep (last time i had the turbos out). that being said, im a bit worried about the lifespan of this cat. the metal substrate should last much much longer than the ceramic ones... btu the way that the metal "foil" is rolled inside (and the thinness of this foil) makes me worry about the consequences of backfires leading to mis-shaping the delecate foil on the inside.

who knows... we'll see how long it lasts.... either way, ill be running one (or possibly two) of some sort of metal substrate cat on my 20b FD (be that the knightsports one or a generic metal substrate one) as i really like its effectiveness at scrubbing the air as well as the decent flow charachteristics. JUST SAY NO TO MIDPIPES!! they freakin STINK and smell up your clothes and hair, are bad for you to inhale, and most importantly are bad for the environment! i dont want to be responsible for destroying our air quality so i can squeeze 5 extra HP out of my ricer fart can. if you want a car w/out a cat get something from 1965.... otherwise just use a cat. if its good enough for my 20b, its good enough for you ! -heath

(PS id be happy to answer any q's about the metalit/knightsport cats... and can also direct you to some of the generic ones that just need to be welded in and are much cheaper.. feel free to throw a post or a PM at me. later)

 

have anyone taken the stock cat and have it modified with 3 inch pipes?? I thinking about this mod...