If I had a car that could easily pass emissions testing (in IL, the vac is hooked up to the exhaust, nothing major) would the same car fail with a Powercore race cat?

I am not willing to run test pipe, and to my understanding this isn't just a straight pipe.

So pass or no pass?

 

ive seen most cars equipped with performance cats fail. mainly cause it doesnt get hot enough for the catalyst material to do its job cause it flows more, whereas the stock cat has a tiny mouth on it that creates backpressure/heat