jammed up exhaust pipe

[jerry]

took the exhaust down pipes of the italian flag 1997 700 monster i bought last year ,, as i want it to be polished only problem is the rear down pipe is seized to the front pipe ,, was a real wrestle to get off ,the clamp came off easy , now on work bench in the vice it wont budge even with oxy heat , penetrating oil, big hammers , pipe wrenches ,, massive weight ,, it seems that its welded together somehow ??