Hmmm . . can be easy, can be hard...
What sort of car ? ( I6 / V8 ? ).
I know I just got a set of pacemakers put on the EL8. While manuevering them in wasn't incredibly hard ( undoing some of the bolts removed much skin ), they were a different length tot he stock extractors, and hence required a cut & weld of a new flange . . . Hence I took it to an exhaust shop to do ( lazy & in a hurry ).
Apparently the pacemaker recommended fit time on my set was 2.5 hrs, which according to the muffler shop, isn't generous . . .
I guess the summary is, if it doesn't need welds, doable but can be a struggle in parts ( you will probably need to remove some other minor parts ). You'll want a hoist or nice high stands tho . . . no room = the suxors