I had to replace a head gasket on my car at the begning of the year so I finally got around to replacing the 181 HP cams with a set of 204HP cams from an earlier 960. (Just did a straight forward substitution without any other changes. No new lifters or .etc.)

My subjective evaluation is that my 0-60 time brobably is slower but that the 60 to 80 time is drastically faster. Overall I like the new characteristics better. (Makes decking the throttle to cause downshifts worth while.) Torque is still more than adequate around town as long as you aren't into stop light GPs.

BTW I've replaced the exhaust on my car with another OEM system and cut the old one apart to evaluate it. I suspect there is little to be gained with a bigger CAT back system. Remember that the gases are cooling as they travel down the system and hence are requiring less space.
--
'96 965, 16' wheels, rear 18mm bar & Koni + 204HP cams at 123K. Had '85 745 Turbo Diesel for 200K.