If you are interested in the GTM at all, I recommend joining the FFR forum at thefactoryfiveforum.com.
I've discovered several aftermarket mods to make to this car, some for aesthetics, some for comfort, and others for easy of fabrication and construction. Members on the FFR forum were very helpful in making this list, see the thread below if you want more info.
https://thefactoryfiveforum.com/showthread.php?27977-Help-me-make-a-GTM-mod-list
FFR Mods - Options provided by FFR
Heating/AC - I live in Texas, this is a requirement
Front Splitter
Rocker Extension
Spoiler
Telescoping Steering - this is specific to your donor car's steering column. Mine is
Cold Air Intake - Removed. Apparently, only works with LS1
Fender Louver - Removed
Non FFR Mods
Window Stops - prevents window crashing inside the door
http://vraptorspeedworks.com/window-down-travel-stops/
Stereo Panel - seals up the cabin a bit better
http://vraptorspeedworks.com/stereo-close-out-panel-36/
Skids - this is a very low-riding vehicle. Helps prevent damage
http://www.norcal-cobras.com/store/r...e/gtm/gtm.html
Window NACA Ducts - Gets fresh air to the engine bay
http://vraptorspeedworks.com/wing-wi...ca-ducts-pair/
Rear Body Vents - exhausts hot air from engine bay
http://vraptorspeedworks.com/custom-...dy-vents-pair/
Both Louvered Belly Pans - heat management
http://vraptorspeedworks.com/louvere...all-trapezoid/ and http://vraptorspeedworks.com/louvere...-narrow-panel/
Rear Hatch Replacement - fresh air and heat management
http://vraptorspeedworks.com/rear-ha...acement-panel/
Note: This replaces the rear glass that FFR ships out.
Kooks exhaust - FFR provided exhaust does not comply with LS3 crate engines
http://vraptorspeedworks.com/complet...xhaust-system/
Note: This replaces the exhaust that FFR ships out.