the GTP has a better aftermarket support, the GXP does too just not as much.
the GTP would have the LIM gasket issue, im sure you aware of that being a GM guy.
the GXP has trans issues.
04+ don't have the LIM issues like the 97-03s we did get the aluminum gaskets.
Cry havoc and let slip the dogs of war.
2004 Saab 9-5 Aero - WAHSAABI - Way too much power/Koni FSD & Hirsch Springs/Big Sways - DD/AutoX'r
2007 Ford F-150 Lariat - 5.4L V8 - Bill secretly likes it
2015 Mitsubishi Outlander Sport SE - Wifey Mobile