Brett - I've looked at the Pypes, Flowmaster, Parts Place, Magnaflow, etc. The Pypes web page claims their downpipes don't fit the stock manifold and they haven't yet responded to my e-mail asking for a solution. That's probably the system I'd end up with if they have an answer, though.
Has anyone with a 326 or 350 changed from a 2.25 to 2.5? What happened to the 'seat of the pants' response?