Can a muffler shop weld a muffler that has a 3 inch inlet onto 2 1/2 inch piping?

Yeah, they should be able to do it fairly easily. Might not look too pretty if they don't know what they are doing.

yeah....most likely
they just need to get a peice to go in between the two sizes, shouldn't be a big deal

~E~ 1999gs
AEM C.A.I./GS-T exhaust/Magnecore wires/Iridium Ngk's/Custom mesh Grill/Upper F/R strut tower bars/TB bored to 55mm/AFX UDP