[Help with sale price]

Here is my experience on the retail side:

 

I took two of these trucks in over the last year one with 80k miles, the other with 55k.

 

One sold at $21,000 and the other sold at $18,000. Both were super clean, and stock other than exhaust, and some visual modifications.

[2003 Silverado SS Dyno numbers. Chart included. Is this good?]

That is impressive. I just finished installing a whipple onto mine. It is pulling about 5psi. I'm similarly equipped to yours short of headers. I'm glad to see numbers that high, as I haven't dyno'd mine yet.