I currently have the 2.5" magnaflow catback and would like to replace the magnaflow mufflers with magnapacks, can it be done? Will they bolt right in with out any welding or modifying?
IMHO, yes it can be done, but you'll have to tinker a little bit. It wasn't as simple as purely swapping them out & re-bolting things back up.
IIRC, a fellow '01 owner had to have an exhaust shop use a "pipe expander" in order to get a good fit for joining the Magnapack mufflers into the rest of the Magnaflow catback (he was in the same situation you are)...so, don't be surprised if it takes a little work, but it CAN be accomplished - not a big deal!