Secondary Cat
 

Quick question: Does removing the second cat affect the performance of the engine? Does it throw a Check Engine Light?

How about smell? fuel economy?

Thanks!

Yes, it increase hp as you open up the exhaust more
No, 2ndary cat is after the sensor which will not throw a CEL
Negligible, as you still have primary cat
Negligible, might even increase mpg

All of these true, just installed my Motiv test pipe (no cat/no resonator) with my stock catback (soon to be replaced).

No CEL

No more smell, slight increase in exhaust tone -will be much louder with catback-

My MPG has gone up, not sure how reliable the fuel counter is but it's about .5-1 mpg better than prior to the change.

As for increase in power, I would say the delivery of power is smoother, TQ dip isn't as bad, and top end is slightly different. I actually see most of the improvement below the 5k mark (where most of my driving is anyway) and it seems to pickup a bit quicker. Not a night and day difference, but worth the ~200 it cost me.

There's more exhaust smoke for sure on a cold startup, but I could care less about that.