The front manifold has lots of crap around the ports which impede flow quite a bit. Grinding down this crap and smoothing it out was at least 2 hours itself. You don't need to do it, but every bit helps! Also, besides the cat material, there is a cotton type wadding material and TWO steel wool bands in those pre-cats as well. I really wanted to make sure the front manifold was clean, and removing it is the only way to do that IMHO.
The rear CAN be done on the car, but you risk getting cat material in the open exhaust ports if you get too vigerous with the screwdriver banging away at the cat. Practice makes perfect Puck, and I bet I could do the job in half the time the second time, but for the novice to Duratec manifolds, it's a long job with lot's of extentions and tight confines. In the end though, it was worth it..
Alex
