Has anyone here done cat-back exhaust? Is it worth it? I found some clips on youtube but I will like better some feedback

 

well decided to go 2 1/4 all the way!

 

will that pass smog

 

Well it passed with no problems

 

Hmm i need to get me some new cats ive never had to do the smog stuff before. i hear alot of people saying that all aftermarket cats would not pass only the oem ones will pass the smog

 

Hogwash! You can change anything after the O2 sensors.
On my V6 3.0 ltr it has 2 pre-cats with O2 sensor before and after each pre-cat. A little further down the exhaust line there is another main cat. I changed all the exhaust piping right after each pre-cat due to the poor design, flow. I also changed the main rear cat to a Magnoflow 1/4" bigger than stock to match the Mazda speed cat back size (and most cat backs) and to match my upgraded crossover true "Y" pipe (dual 2" to 1 2.5"). It flows and sounds great. Easily passed emissions.

 

Ok thanks. ill have to look into it.. when i got the car from this guy he had cut one of the cats off. and i have to find a new cat eather oem or aftermarket. im new to the smog stuff. never had to deal with the cali laws before. im hating it so much..

 

Yes, you must have the same amount of cats that car came with. Hopefully he cut the cat off with no O2 sensors around it.
Magnaflow also sells exhaust manifold/pre-cat assemblies which may be cheaper than Mazda and OE equivalent if needed as well as spots for O2 sensors.
Click: Magnaflow has Catalytic Converters with Exhaust Manifolds