to anyone other than an enthusist the aftermarket accessories like the headers, the chip, cross drilled rotors and resonator add little or no extra value to the car.
I guess my answer to your question is; to the average person your car is only worth book value. But, to someone who understands what the aftermarket accessories are about it might be worth more to them.
If you market your car to the right person you may be able to get closer to what you want for it, but, you may have to be patient.
