Alright, on my stang right now, she has four cats on the exhaust system. If I were to go with an X-pipe that has only two cats on it, am I still going to pass emissions? And I'm looking at a pretty good horse power gain with an X-pipe right? Or would an H-pipe be better? Thanks-- Paul

You should still pass emsissons with the 2 cats, but when you have parts that aren't emissions legal, then you have a problem, it doesn't matter if it passes out the pipe, if its not emissions legal. I think on a normally aspirated, mostly stock 5.0 motor the X-pipe is worthless unless the motor is modified somewhat or has some form of forced induction. I hear they work great with superchargers and the newer 4.6L Mustangs.

You didn't mention what year your stang was or which state you live in, but I happen to like the X-pipe myself. This is kind of none technical response but, I just like the sound of an X-pipe better then a H-pipe.

As to the power department of an X-pipe, I think they are equal, or possibly better then a H-pipe, but they are more expensive and like Jesse said, they won't do much for a stock motor. But I would still recommend it. Like any mod, it helps to be prepared for the future! Besides, you got to love the sound

Emissions should not be a problem. Just ask the manufacturer if it is emissions legal in your state. They have to tell you and they will. Don't run anything that won't pass emissions! It a big headache you will want to avoid!

Me personally I took all my cats off but definately dont do that if you have to pass emissions tests. You shouldn't have a problem with just two cats. If there is a performance shop in your area I would give them a call they might give you a definate answer

I saw that you took all four cats off your car. I have a 2000GT and want to gut the cats on it. What mods will I have to install to beat the computer?

JK00GT

Paul, an X-pipe will be quieter than the H-pipe. Depending on what state you live in, I would get an Off-Road H-pipe(no cats). It will really open up your exhaust system. Do you have aftermarket mufflers? If so, you will get a mean roar with the h-pipe. The X-pipe is the quieter of the two. Good luck.