Originally Posted by Mike@GTM

On the exhaust thing, yes, they'll write you a ticket for having anything other than the stock exhaust...especially in Federal Way. So if you have a cat-back on your car, you're breaking the law. You may get away with it for as long as you own the car, or you can get popped every other week. It just depends on the police officer that sees/hears your car and what part of town you are in. Some of them are haters and other don't care. Drive like a douche and mouth off to the cop, and he'll probably tack it on top of whatever he was going to write you up for...even if he normally didn't care. Also, the more obnoxious the exhaust sounds or looks, the more likely you are to get stopped for having an illegal exhaust.

CARB stands for the California Air Resources Board and is the agency that deals with aftermarket automotive parts among other things. Washington has no such agency. Let me just ask you a quick question. Do you interpret that law to mean that every time you want to register your car in Washington that you have to drive it down to a California smog station to get it certified?

That law basically means that the car has to have one of the stickers under the hood that looks like the one below for California emissions.



That's it. It doesn't require California Executive Order numbers or anything of the sort. However, if you want to interpret it such that you can't do anything to your car, then that is your choice. If I were you, I'd hop onto a local forum and check with other enthusiasts as this thread isn't really intended to be a Q&A on Washington laws.