How big of a difference will there be if I change my catalytic converter to a test pipe?

I have high performance catback and headers installed but I have the stock catalytic converter connecting them, it sounds really good right now but will there be any performance gains, like how much horsepower would be gained from a test pipe and also will it change the sound because I love the sound, it is really deep and not too loud.|||The main thing you will notice is that no reputable shop will do it, and if you can find a shop that will, you will probably need to tow it there on a trailer, pay cash and trailer it away. You then can expect to never have any reputable shop anywhere ever work on it again until you put a cat on. If you take it to the right shop, they will call the EPA, and they will give you a $2,500 fine for removing it, and give the shop that did it a $10,000 fine.





But in a hypothetical situation, you will lose HP and torque by removing it. Modern engines need a certain amount of back pressure to ensure proper scavenging. This back pressure is created by the cat, and most modern cats produce very little back pressure. If you have no cat, your vehicle will blow unburnt fuel out your exhaust, will burn exhaust valves, and smell like @$$ to any poor soul behind you. Very uncool in my book......|||There would be a modest gain (maybe one horse). Most modern catalytic converters are pretty free flowing. They are required by law and to remove one is a irresponsible act.


Now if you want better performance, just get some better headers and maybe a mega-flow catalytic. That is what I did.