Emission's Cali Vs Fed Spec
 

I just found out that my maxima is Cali spec, despite the fact that I live in VA
does anyone know the difference between the two, and can explain it? Isnt
California spec emissions much stricter that federal emission standards, due to
the smog and polution in Cali? How does this affect my options in terms of
performance upgrades to the exhaust sys, intake and so forth. Will it limit
the amount of power im capable of getting from these mods, cause I have to
buy upgrades like a cali spec y pipe?

It was the same problem with me about 2 weeks ago. All 2001 maxima are cali spec. And yes if you change the Y pipe, you will eliminate only 1 precat, not both. First i was thinking that my car will be very unstable due to different flow between odd block and even block.
But after i installed the Y pipe i am very happy with it. Feel much better acceleration at high RPM without any problem.
I am at the dealer now, waiting for advance timing performed.

cali spec has one more secondary o2 sensor, swirl control and one more precat that the additional o2 monitors.

Thanks for the info so far bump.. for more input

01 maximas are NOT cali spec, they are US spec. The difference being that they just have the extra oxygen sensor. They have the same 2 precats and single main cat that the fed spec 00's have.