Yes you most certainly could get over 4,000 for it. Even with exhaust... make the customer pay, it's YOUR car, NOT THEIRS. I had a V6 mustang with full bolt-ons, that had been wrecked 3 times... once by previous owner, I hit a tree, and a deer. I put the car back together myself, and people said you'll NEVER get over 2k for it... I'm like.... to hell with you people I'm going to get what I/ME wants for it. I asked $3500 for it, and I got $3500 for it. It had 180,000 miles on it.
So yes, I would not be suprised if you got at least $5,000 for it. Ask no less, because your car IS WORTH IT. To hell with all the people who want a damn cheap deal... You want/ need the money. I KNOW you can get that price for it. Offcourse I do have experience selling mustangs... I make the customers look unworthy of my car... beggars cannot be choosers. You must make the customer the beggar, not you.