Send a picture. It's tough to say. The minimum diameter of an LS2/LS3 TB is 90mm.
There's a part number stamped on there somewhere, too. You can use it for reference. An after market TB would be reasonably easy to identify.
'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)
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