is it impossible to pass inspection with an aftermarket cat? Do they do any actual performance gains when combined with the right I/H/E? I'm thinking of getting one but don't want to deal with inspection a year from now.... thanks for any advices.

 

actually some aftermarkeT Cats are 50 stage legal.. some companies.. are Random Technology..Magnaflow..I beleive Carsound or how ever u spell it.. and actually u can order larger than stock CATS from them ,which will actually flow better than your stock.. but will run smoother than a straight pipe due to the Backpressure that is made from having a slight restriction.. for some cars