I have a 79 f-250. I know that here in PA that my truck has to have a cat on to pass the emissions inspection (a visual check to make sure all the stock emissions stuff is there). My question is that if I go to true duals, can I just put 2 cats on? I have heard that you have to have the same number of cats that were stock on the vehicle. Mine only is supposed to have 1. I heard that you are not supposed to alter that setup even if it increases the number of cats Anybody??

 

Well to be sure I, would reasearch your local laws(maybe make a call to a local exhaust shop)....I know for a fact on the newer vehicles post OBDI, you need an O2 sensor downstream of each Cat to be legal(I have a 96' F150 w/ a true dual setup that dosen't meet this requirement and therefore is "shady"). Being that your truck should be pre OBD, I personally cant see a Legal issue.... I highly recommend doing the research on the laws. Have you considered maybe a "Healthy" Cat back setup???

 

I know that I don't need an 02 sensor. What do you mean by a "healthy" cat back? Thanks for the advice. I'll be trying to get some more info on what the law will require of my truck.