Quote:
Originally Posted by nakamur21
So if the O2 sensors are in front and behind the primary cat in the exhaust manifold, can you ditch the secondary cat in the front pipe and still pass the OBD-II smog test?
I understand newer vehicles are not getting the sniffer test and are OBD-II only, so even though you can't get a header in CA and still pass smog, you may still be able to get a catless front pipe and pick up 5-7hp.
|
A proper sized high flow cat costs VERY little hp compared to a catless pipe. The big restriction is from higher cell count OEM cats with smaller diameters.
A 2.5" catted front pipe will probably make about 1hp less than a 2.5" catless front pipe, plus the catless pipe will be raspier and louder. It might not be noticeable with the stock header, but if you go aftermarket you'll hear it for sure.