I snapped one of those studs when I installed my cross pipe. I believe it's actually possible to drill out the stud and put a new one in while the downpipe is still attached. I think someone else on the forum was able to do it that way. If the downpipe does need to come out, I found it easier to drop the downpipe out the bottom after removing all the heat shields from it first. It's a tight fit, but it'll drop down there. It's such a hassle to work with the downpipe, I'd recommend just upgrading it while it's out, if that's a mod you were ever planning on doing.