California smog laws?
 

If I put headers on my 3.2 I will eliminate the first set of cats, leaving only the second set. Can't avoid it I guess as this is part of the size of the headers. My question is will this effect my CA smog test? Is the car clean enough, assumming my engine is in good shape, that it will pass smog with one set of cats?

I did the same thing and my car passes smog, but just barely. HC tends to be high.

wow... you got lucky passing. I believe the person that did your smog was in a hurry and did not do a visual test. Also if you eliminate the first set of cats on an S wont it cause you c.e.l light to come on (because the 02 sensors are on the first set of cats) and if that happens you will fail smog test.

I can't think of a smog station that would know enough about Boxsters to know what to look for. I never got a CEL light from eliminating the primary cat and it's been this way for over 2 years. The key is to relocate the secondary O2 sensors to be behind the second set of CATs. I do have CEL now, but it's probably a MAF problem.

Removing a cat is illegal in any state. If you get the one set of cats you've got left good and hot maybe you'll pass the tail pipe test. Make sure the car is well warmed up before going in for your smog appointment.

On the visual inspection it depends on the smog station. I recently took my CRX race car in to see if it would pass visual. The smog station pulled out a big book which told them everything to look for on my car. If you go to a shop that's anal and checks, then you'll be screwed. When I smog my Boxster though they don't look underneath it and they don't even ask to look at the engine.

I've found this theme to be true to almost every porsche. Most smog shops just assume the car is louder then "regular" cars because well its a performance oriented car. Even if they thought different, most wont want to put the car on a lift to check for issues anyway and it's probably 100% assured that they wont even know how to open the hood of the car regardless.