the words "asking" and "firm" do not belong in the same sentence

fwiw, i think $10k is a bit high. if your car had 50k on it i think that
might be plausible. the only mod that would demand a premium asking price, imo, would be a motor swap or forced induction.
i have plenty of used car sales experience

all of them modified. take it from me, most mods dont mean $hit when it comes to resale value. i can
almost guarantee you that you could put that car back to stock and get nearly the same selling price. maybe, a grand less.
just look at Lowbudgetracing's csvt for sale. that car has some
serious mods done to it and has
low miles on the motor. it didnt even come
close to your asking price on ebay, let alone he had a buyer back out at just $7k.

i dont mean to sound like a jerk. just trying to be helpful. if you really want to sell your car then i would hate to see you sitting on it for month after month because the asking price is too high.
fyi kbb says your car is worth $5680 (in excellent condition). $5k extra for some basic bolt on mods??