Selling Value for a Friend's car?

Friend of a friend wants to sell his car but has no idea on what it is worth.
Here is his description of it, I know nothing about the car, not even the colour. EDIT - Car is blue with leather interior. Assume Deep Impact blue.

2015 Mustang Ecoboost Convertible, 6 spd auto
61,730 km.

Steeda lowering springs (lowered about 1-1.5")and Camber suspension upgrade
Roll bar (lighted)
MRT exhaust system
MRT boost (about 290 horsepower now)

Bought some winter tires and rims for it just in case but not winter driven.

Anybody have some thoughts on what it's worth?

I'd say it's in the 16-18 range depending on condition and mods/colour.
There are quite a few PP1 Ecoboost's for sale with recaro's for just over or just under 20k.

Best to cruise Facebook Marketplace / Kijiji to compare. Does look like resale of the EB is hair or three soft vs GT cars but bet this time of yr vert is a plus.

EDIT - Car is blue with leather interior. Assume Deep Impact blue.

Online Black book indicates a $22,000 trade-in value?

It’s got leather so it’s a Premium trim. I’d say about 28K is a good place to start. And now is the time for convertible sales.