On my 06, I replaced the 6.5 w/ Alpine.. Very nice and ran about $150. Major difference.. Installer said they were a good fit ..
2007 GXP mysterious (sold.. I sorry)
leather, monsoon, 6 CD, headliner, sport pedals, polished aluminum, custom front grille, GMPP stage II upgrade, GMPP exhaust, K&N drop-in, stubby antenna, Kappashield, XM, no front plate (2 tix so far)
2006 mysterious # 5330 (SOLD)
NASSOA # 87