The Automatic transmission in both the GT and GXP is the 6L80. The GT has 2.92 Gears and the GXP has 3.27 gears in the rear end.
The Manual GXP uses a Tremec TR-6060 with 3.7 Gears in the rear end.
'09 PSM G8 GT - OPG Intake, DOD-Delete w/ Stage 1C 218/229 .600 Lift 117.5LSA, Kooks 1 7/8 Mids, Solo Axle-Back w/ X-Pipe, SuperPro Bushings (Front and Rear). BMR Sway Bars (Red)
"If you want to criticize someone else's work, be sure that your own is in order first."