Chaddy

...that might make piggies illegal, but not aftermarket DPs. I think the law also says it is illegal to replace catalysts with non-OEM catalysts before 50,000 miles.

Then there's the X-factor of the mechanic doing the inspection - will he/she freak out if they notice the O2s have been relocated.

I've been thinking lately about gutted pre-cats + software w/ CEL disabled for the secondary O2s so the DPs remain totally stock-looking, but don't know if the fault would still show up when scanned.

lastls1

I've had email chats with my state and the federal EPA and there is no enforcement as far as I can see. Who will turn you in?? Nobody I know.
As to modifying exhaust systems remember that if you CEL is ON, your ECU is in limp mode (open loop) and you are probably getting lousy gas mileage and poor engine performance. The pre-cat O2S are used to set the fuel/air mixture correctly and run it closed loop. The Post-cat O2S are there to see if the cats are working. They need to see an almost oxygen-free exhaust stream at that point. Any excess oxygen triggers a CEL and usually a code that says the cat(s) is/are not working based on the post-cat O2S readings.
I have a '99 Mustang with no cats that passes state emissions tests. NO. I won't tell how.

Chaddy

...mechanic sees the modified exhaust, decides for himself what is legal, and refuses to put a sticker on the car. I am certain I can pass a sniff test with piggies, I just don't know if that's enough to get the sticker from the mechanic's point of view.

Switchblind360

Air chisel is the way to go. Otherwise, you can always have the exhaust shop do it. Just tell them its for a "track only" car.

OR, just have them weld it back together. I know there's guys that used to do it without cutting the pipe below the pre-cat, but it is incredibly time consuming and a PIA. Plus you don't know how much crap will get stuck in your main cats.

VR_Life

Precisely because they look unmodified and exactly like stock.

VR_Life

Perfect ! Thanks ;-)

Chaddy

...welded up stock O2 bungs.

I suppose one could try using the local idiot wrench, hoping they wouldn't notice, but those guys are often too stupid to breathe with their mouth closed, let alone touch my car.

Do you have to go to a state agency in CA to get inspected, or just the shop of your choice?

VR_Life

They check that the parts look stock, have stock emblems & part numbers and that is all they know.