Ferrari used to have a investment section on their website that told you what to look out for in each model and year. You might check to see if they still have that up and check out the pro's and con's of that model/year.
Also, I think you are crazy for wanting/thinking you can put 20K on that car a year. Not trying to bash, just my opinion. The reliability just isn't there. It would be a bad ass car to own though.
If you can afford to put 5k in maitenance into it a year I would say get it.
CJ