$10-12k Max... But it is going to take some time to sell.

There is a 91 vr4 going on ebay right now in mint condition and only 48k miles and they are asking $12.9k.

Mitsubishi : 3000GT VR4 in Mitsubishi | eBay Motors

It would probably sell before yours does as it is stock. Most buyers will not touch a car that has been modified and that is your biggest issue. You have a very niche market to sell you car too so that is why it will take time. You will never get what you want out of it or get back the money you put into it.

Hell even a classic car full restoration will never see the money back that was put into it......