im gonna be fabricating my custom exhaust within the next few months, and i just have to know something. I live in california, so they are really strict about emissions and so fourth... If i added 2 extra high flow car converters along the exhaust piping, will that muffle sound and cause even lower emissions? it wont be hooked up to the emissions system or anything, it'll just be 2 extra cats that are gonna act as mufflers/cat converters... will it be possible to pass emissions w/ stock cats and these high flow ones? im planning on going with headers, intake plenum, intake, ecu reflash, flywheel and crank pulley (do these have an effect on emissions?), and some porting/polishing, etc. this would be great to know so when testing time comes around, i'll be saving time... but if i cant pass, why spend all the money on the mods?

 

put back your OEM cat when you go for smog check.

 

can the OEM cats pass headers, and all the other mods i put up there? if so, im not gonna bother with a second pair of cats!

 

to be more exact, pass crawford headers

 

yes they will.

 

It may be able to pass, but if you are using them like mufflers I would assume you would have them located in the same area?...

If they are, they are too far from the engine. The cats need very hot exhaust gas to heat them up to operational temperature. ...But if they are located far from the engine they may not scrub the exhaust very well.

The exhaust gas cools very rapidly as it travels through the pipes and the cats may not be able to heat up enough enough to light off.

 

they would be right after where they are right now... like in the Y pipe connecting to the cats... but if the stock cats can take care of the extra emissions the engine is pushing out, i wouldnt need to add more cats... but can the stock cat really cover all the increased emissions? isnt that why its not CARB exempt? because the stock cats cant handle the new increased level of emissions the part pushes out? or is it just because the part is an upgrade and the CA gov doesnt like it?

 

There is a good chance it will pass smog but you won't really know untill you try. If you are running excessivly rich all the cats in the world won't help. If you are running excessivly lean, additional cats will only drive up the NOx levels.

Run your car on the dyno/sniffer to see that you are within the correct A/F range and you will have a better chance of passing.

 

so if the a/f ratio is okay, the OEM cats may be able to cover up everything okay? can dyno/sniffer determine if i will pass smog or not?

 

No. It will only let you know if you are in the ball park.

 

ahh.. the Z is in the zone of 3.0 for smog right? it says on the retail sticker... does that mean i cannot go any higher than 3 on the scale?