Is it your manifold or your downpipe that is loose. Downpipe is futtery to do, but you can give yourself space to work, by taking one of the bolts out of dogbone mount and swinging engine foward for space. The nuts that hold this on, press against springs, and are awkward to get back on (dont be afraid to cut a wee bit of the spring to make things easier). its two nuts and its off. Get a new sealing ring from reno, for reassembly. Manifold can now be taken off, soak well in wd40 several times and leave before attempting to loosen nuts on manifold studs. There is also a support arm, which will need to be removed. New gasket and slap it back together, remembering these annoying heatsheild around manifold and downpipe. Not sure of that helps you