Agree. There would be probably no measurable performance gain by this. Maybe a little more aggressive exhaust 'note'. A hard case to spend likely several hundred dollars for the custom-made installed system. The 2007+ rear fascia may have had the cut-outs for the dual exhaust tips while the earlier ones didn't. The Pacifica didn't change much even with the mild front end styling refresh. Something must be different about the earlier ones (possibly the cut-outs?) why they aren't included in the model year coverage of the dual exhaust kit. The 3.5L never had duals while the 4.0L did. Possibly a phone call or e-mail to either of the companies would give us the answer why not. I see that Walker's brand Pacifica catalytic converter is the same part from 2004-2006, so maybe the entire exhaust system did change for 2007+? Pipes would likely have to be custom cut and formed.