I was going to (try to) answer this when I saw it, but wasn't sure what headers meant!
On mine, there's the block > manifold > downpipe union > centre pipe > midbox > backbox.
The manifold is a pig to take off, if it hasn't been done for a while because 2 of the nuts are quite inaccessible. There's 8 studs in total, with 2 buried under the manifold, and its tough to get a decent grip on the rusted nuts. I removed mine with the engine out, and it still took some angle grinding to get the old nuts off, and a stud extractor to remove the old snapped studs!
I couldn't remove my downpipe from the manifold for love nor money, the bolts were completely round and rusted to high heaven, so it was a non-option for me. Given the bolts were sprung, I didn't want to grind them off, because assembling would be a pig. I've never done it in the engine bay, but I seriously doubt it would be easily done if it was in the same condition as mine.
As said, if you can get access to those two sprung bolts, which I couldn't from below or above without using an angle adaptor on my socket extension and simply losing grip, then getting the car high, undoing the centre joint, it should slip down and out.