Question about downpipes and smog

[Streichholzschächtelchen]

Smog time is coming for me, and my question goes as follows. If I'm running stock manifolds and a new CA legal cat but my downpipes are cracked can I have new downpipes made in stainless, stock diameter and stock routing? Or do I have to buy some form of bolt in replacement?

[3vilE30]

I think you should be good as long as you have your o2 sensor at the stock location, if it passes out the tail pipe most smog techs don't care about little stuff like that.

[Streichholzschächtelchen]

What if I have the magnaflow cat for e30 in CA with o2 sensor bung on it, can I just use that bung? It has the right eo number and everything.

[Tinkerer007]

What if I have the magnaflow cat for e30 in CA with o2 sensor bung on it, can I just use that bung? It has the right eo number and everything.

A SMOG referee told me the O2 sensor needs to be within 6 inches of the original location...

[Bimmerman325i]

I would take the car to your smog shop of choice, point out the issue, and ask what are your options.

They are the arbiters of whether it's allowed, we on the internet are not. I've had enough headaches that I wouldn't want to chance them seeing welded pipe between manifold and cats and freaking out.

[MR 325]

There is no law about replacing 30 year old exhaust pipes. If you have the stock manifolds, proper o2 sensor location, and CA legal cat you'll be 100% fine.

[YosemiteSam]

What if I have the magnaflow cat for e30 in CA with o2 sensor bung on it, can I just use that bung? It has the right eo number and everything.

O2 sensor mid-cat is very different from O2 sensor in the down-pipe.
Mid cat is used OBDII to tell if the cat is working, while the O2 in the down-pipe is used to steer the mixture.
If you just hooked it up to the stock ecu and it was mid-cat, the car would probably fail smog both on visual and on numbers because the mixture would be all sorts of wrong.

[Streichholzschächtelchen]

Sensor is before the catalyst.