welding on apexi

I just got a apexi n1 muffler, no exhaust just the muffler. Now when i take it to go get it put on will the muffer weld directly on to the stock pipes or do i have to get my other pipes custom to fit the apexi muffler.

they cut off the old muffler, then if needed they will attach a new section of piping. the Apex muffler's inlet should be close to the size of your car's piping, they will just weld it together.