which setup would be better for my car, one cat or two? Does it matter ?

 

Loose the iron box collector and go for a dual header, then go dual all the way back. With 2" pipes & cats you gain some noticeable high end power without loosing low end torque. The sound level is a matter of preference. I love it..

 

Which is better for your car? Well no cats is better for your car. Better fuel efficiency, more HP, less heated exhaust. Of course its not good for the environment, passing emissions, noisy, smelly, etc...its all preference man...