yes. you will pass emissions as long as there is no SEL on. they just go by the OBDII plug to verify emissions.
when i changed my cats. i didnt gain anything in the 1/4 mile. it stayed EXACTLY the same. the exhaust on our cars are already pretty good from the factory.thats why changing the midpipe and muffler gains are so minimum. unless you have a computer upgrade to tune it, i wouldnt even bother with it. the money for the cats and install, i would've gotten a UTEC in stead for a lil more money.

 

My install is FREE, my brother is an Infiniti mechanic....

I also plan on getting a UTEC and having MRC have a look at the car and tune it.

Question: Do I NEED to tune it to be "safe" or just get the most from my mods?

 

to get the most out of your mods.

 

My butt dyno validated the Crawford cats.

I felt the small performance gain when they were installed compared to how it was before, and they do sound great. I haven't had any issues with them(no smoke, no smell, no rattles) thus far (they were installed over one year ago).

I just don't like the idea of my car running its' @ss off on a dyno.

 

We have the new version of the Crawford cats in stock! http://www.mynismo.com/products/?id=2726

You should be able to pass smog in CA with these cats, there is still a catalyzer and will not givve you a CEL. The stock cats are the most restrictive part of the exhaust system so changing out to the Crawfords will help tremendously and should prove a nice gain in power with headers and a cat back exhaust. These cats will change the tone of the exhaust but should not make it that much louder.

 

I know this topic has been beaten to death 200 times over but I still must ask ... Do you have any quantitative evidence to prove this statement?

 

http://www.fastintentions.com/350z.htm

dynos there for stock vs. stock cat+catback vs test pipes+catback.

i found posts on the forum that claim "almost" the same gains for hfc as the test pipes, but i dunno if i recall seeing a before/after dyno for any hfc.

 

ive seen this too...i want to say it was by 98intrigue or nismo g...

 

https://g35driver.com/forums/engine-drivetrain-forced-induction/111376-dyno-comparison-high-flow-cats-vs-test-pipes.html

he didnt post the dynos on that thread...but i think he has them some place else..just too lazy to find em is all

 

I threw out my dyno charts from a while ago but the very first mods I had done was Crawford high Flow cats, UR Pulley and a Popcharger. I did not do a per/post dyno. After that I added headers and the headers only gained 3 HP. After that I installed a NISMO cat back and went to the dyno again and it gained 14HP from the exhaust! I know the exhaust did not make that 14, probably half that and the rest probably came from the cats and headers.