I want to run an electric exhaust cutout before the cat on my 89 Formula 350. What size is the stock piping before the cats so I can get the right size cut out? Will it make my car any louder? My Flowmaster muffler is loud but I want something louder than all the civics and neons around my house.

 

You said cats, plural, so I'm guessing you have the dual cat setup? The stock y-pipe there is 2 1/4". It will be extremely loud as you're basically running open headers. A better solution is to run the cut out at the end of the i-pipe, just before it goes up and over the axle.

 

So if I got a 2 1/4 electric exhaust dump, I could put it in the pipe before the cats and it would unload both sides, right? I don't care how loud it would be, I doubt racing at the airport, the special police can't tell a plane from a car. I kind of wanted a louder sound anyway.