Van Check-up

[tin-box]

Hello all-
I am possibly selling my beloved Vanagon to a friend. My friend is excited and wants to take the vanagon on a couple of trips, including one to Austin, TX. About 1500 miles (?) I want to keep this friend, and thus I have brought my van to a mechanic for a go over before the sale.
The mechanic says before he can check the engine seals and compression, he must first take the muffler, or part of the exhaust off. does this sound right? Also, I am wondering, if the van is leaking, this is a sign that the seals are damaged. If the compression is good, and it's leaking, is there a possiblility of catastauphic failure? Or does it just get to the point where it's just leaking like crazy and the seals need to be replaced? I guess what i'm asking is what I need to educate myself about so I know how to talk to the mechanic. I have read some strings, but i'm still not sure. Any input?
J