[BayernMuenchen]

I know nothing about exhausts and have seen cat/back and turbo/back mentioned numerous times. Anyone mind explanining the difference?

-Mark

[uberschnell]

In California, one might pass exhaust inspection and one will not and may get you fined $2000. Both are illegal.

Cat back = from the primary catalytic converters completely back, eliminating the second set of catalytic converters and resonator.

Turbo back = from the turbo outlet completely back, eliminating both sets of catalytic converters and resonator.

[Ryan@Motorwerks]

That's not always true though magna, you can put racing cats on a turbo back and still pass emissions.

[uberschnell]

True, I meant in the truest sense of "turbo back"

Still, should be aware of the legalities. Replacing a cat without jumping through some major loops in California is illegal.

Now, that hasn't stopped me personally--

[uberschnell]

California has a visual inspection also. If the tech has a schematic and knows what to look for you could also be screwed, even if you passed the test.

Lots of good ways to get around this though, like gutting the cat.

i'm going away now...

[wj4]

Originally Posted by 335e90

That's not always true though magna, you can put racing cats on a turbo back and still pass emissions.

Yes, that is what I did in my previous car. I put in a hi flow cat instead of a test pipe for 3 reasons...1. it would throw a CEL on that car, 2. it would give off a sulfuric stench, 3. the fine in CA of driving on public road with no cats is steep, around $2,000.

To the OP, the catback exhaust is just that...exhaust behind the catalytic converter(s).

The turboback exhaust replaces the whole exhaust line right after the exhaust manifold(s).

[Chesmu]

all of which should improve HP and sound.

[BoostedBMW]

To answer the original question... catback means that it goes back to the cats, which on the 335 means that it replaces back to the downpipe since the primary cats are in the downpipes. Turbo back means that it also replaces the downpipes and bolts up to the turbine side of the turbos.

[Not Ur Avg 3]

cool stuff, and thanks guys
i was kinda confizzled bout these things too

[BayernMuenchen]

Thanks so much for the clarification. Much appreciated.