Can someone help me with a price please!

I am looking to sell my 2004 GT Coupe in the VERY near future. The one problem is that it is currently financed. Other than that everything is clear. I need help on a price because Carmax and Autotrader are not even going to give me what I owe. Worst case scenario, I put some of the stock parts I still have back on and sell it that way, then sell the afterarket parts I can. Here is a list. I will post pictures in the morning when I get home.

-40,010 mi
-5spd

Clean Interior
-Leather seats
-Ice Cold A/C
-Billet A/C knobs
-Billet Pedals
-Cigarette Plug
-40 Anniversary Plaque
-Short Throw Shifter
-SCT Handheld Tuner

*Clean Engine
-Upgraded Fuel Rails
-UPR Products Fender well Cold Air Intake
-BBK 70mm throttle body
-Stock Throttle Body Included
-BBK Shorty Headers (L/T 200mi)
-BBK High-Flow Cat Mid-pipe
-Magnalow Magnapack Cat-back Exhaust (L/T 200mi)

*All quality fluids
-Valvoline Synpower Synthetic Oil
-Royal Purple Power Steering Fluid
-Valvoline Synthetic Brake Fluid

*Powertrain
-5spd transmission
-Short Throw Shifter
-373 gears
-Eibach Lower Springs
-Chrome Wheels
-Good Tires

*Clean Exterior
-Mach 1 Grille Delete
-Stock Grill Included
-Mach 1 Chin Spoiler
-Sequential Taillights w/ Slow Flasher (AutoTrix)
-Custom Airbrushed Pony Emblem Black emblem with skeleton horse
-Stock Chrome Pony Emblem Included
-Chrome 4” Exhaust Tips
-Dark MUSTANG Lettering on Rear Bumper
-New Headlights (20mi)
-Locking Lug Nuts
-5% Window Tint All Around
-Fog Lights

The maintenance records are not on hand. I take it to the same guy that changes our patrol car tires and all I pay him for is the use of the lift. I buy the oil myself and he puts it in. I have only put 8,000 miles on it so the oil has only been changed twice. My mechanic can speak for the vehicle if need be. I do have the records from the exhaust install, and all other parts I have purchased. Non-smoker/no odor. It is a weekend car and I don't drive it all that often, it just sits in the garage day in and day out. I still owe a little over $10,000 on it.