On mine, it was pressed in. Mine had actually become loose and "unpressed" itself, I found this out when working on the exhaust several years ago.
Any bolt or stud on an exhaust system tends to become pretty hard to work with after a few years of heat cycles and running in the wet and getting saturated with road 'salt', etc. I replaced mine with stainless steel bolts that were liberally coated in copper anti-seize compound.

 

LOL! I like to recycle old threads.

I also may do what you recommend and remove the studs. I'm thinking of doing what Adam C. did with his stock cat:

"Your stock cat has an effective diameter of 2 1/8 inches at both ends. The flange welds are on the inside of the pipe, obstructing the flow. It can be opened up to 2 1/2 inches fairly easily. Going from 2 1/8 to 2 1/2 is a big difference. Do the math. It works. I removed my cat, re-welded the flanges on the outside, and then ground off the inside welds until they were smooth. I was able to feel a noticeable difference in power after doing this."(Thread)