If you buy the system from Volvo it comes with a life-time guarantee. I got my second system for the 740 for free.

I just put a Volvo system on my 960 last year because one of the mounting brackets rusted off and it was hanging at an angle. The rest of the system was still quite good even after 7 years of New England salted roads and my 6 mile commute twice a day. I sprayed some cold galvanizing paint on the brackets of the new one to prolong the time till changing it. I never expect to buy another system for this car.
--
'96 965 with 16' wheels at 120K. Had '85 745 Turbo Diesel for 200K.

I tried this once on an exhaust system I replaced on a Camry. (Although I didn't try to do the inside... that's impossible) I used high-temp black "stove paint" on the welds (at flanges and where the inlet and outlet pipes are welded to the muffler) -- because these are the weak spots where the systems always fail. It did work for almost 2 year. What I mean is that the paint stayed on, and there was no rust there.

It's certainly true that exhaust systems rust predominantly from the inside, out. But if you can curb the exterior rust, then maybe the system will last an extra 12 months... who knows. (that's a completely unscientific guess, by teh way).

That being said... I did not paint the muffler seams on the last two systems I intalled on my Volvos. I just didn't feel like taking the extra time.

Jeff Pierce
--
'93 945 Turbo ( one kickass family car ! ), '92 Mercedes 190E (my daily driver), '53 Willys-Overland Pickup (my snow-plow truck/conversation piece -- sold to a loving home), '85 Jeep CJ-7 w/ Fisher plow

I wouldn't bother. Exhaust usually rusts from the inside out. The exhaust system builds up condensation and unless it is burned off regularly through a long drive (30 min +) it stays inside the mufflers, etc. and eventually causes the system to rust.