ended up taking the exhaust manifold out without much pain actually.
once the manifold stray was take off (mine is useless because it rusted through), it was easy to reach the 2 lower bolts. the upper bolts were taken with an articulated ratchet. percussion was enough to free them from their treads.

then i drilled through the rusted bold and remade the threads. buffed slightly the exhaust to take off a bit of rust but too much so that i wouldn't seal properly. get a new gasket put everything together with anti-cease and it's ready for battle!

got to say, if you a friend-genius to show you how, it greatly helps