27151. No person shall modify the exhaust system of a motor vehicle
in a manner which will amplify or increase the noise emitted by the
motor of such vehicle so that the vehicle is not in compliance with
the provisions of Section 27150 or exceeds the noise limits
established for the type of vehicle in Article 2.5 (commencing with
Section 27200) of this chapter. No person shall operate a motor
vehicle with an exhaust system so modified.

I got this from CA Vehicle Code...

Most mods you do to a car will make it technically illegal. if you do anything to it to decrease the MPG (bigger rims for example), put headlight or taillight covers on, ect. you are able to be fined. Now, some are enforced, some are not. Exhaust around me isnt exactly cracked down on unless yours is EXCESSIVELY loud.

 

save your money and forget the stainless bolts. imo i don't think they are necessary if you use anti-seize lubricant on the threads of a traditional bolt. i've done it for years and it works like a charm. you will get surface rust and they may not look as good, but the threads won't be rusted together.

 

it was those codes that police have that vita said. if it is too loud then your breakin those laws. if it is a good deap rumble and it isnt a nucence then your fine. if you notice that you have a unusually eggy smell when your car is warmed up and driving its time for a cat back aka new cat on back. but make sure it will be a good rumble from a mufflers that you know wont be soundin like a fart can like some ricers have. then it will beake those laws thatvita stated

 

Yes, its not that bad; only 4 bolts + the O2 sensor

Also, I've heard shops not wanting to do it because of the law BS; I don't really blame them- its a pretty steep fine if they slip up; so I'm sure they'd rather just refuse it to be safe.