4 inch exhaust installation

I'm just gonna assume you have a 3" dp that bells to a 4". Yeah, in most cases you have to "massage" the firewall. To get the stock dp off, take a sawsall with a milwakee Torch blade and cut the "cobra head" off the stock dp as far down as you can. Usually that's holding the saw at a 45* angle above the passenger side valve cover. That should get the stocker out. You may have to make more than one cut. And don't worry about the shavings cuz you are on the exit side of the turbo, it'll blow out. As for the firewall....... hold the top part of the new dp in there and look where it goes. There is a pinch weld down there behind the heat shield that needs to be folded down. Make two cuts on the seam about an inch on either side of where the dp goes. Now the fun part. Some people gut it out and beat it down with a hammer. Some use a ricer car scissor jack. The easiest by far is a port-a-power duck bill and block of wood. That's what I used, it took like 3 minutes. It takes longer to set it up than it does to bend it. Best $80 I ever spent on a tool. But you should only have to bend it back an inch or two. Not much. But you don't want to let the dp rub on anything. Anyway, I hope that helps.