I was curious to know if you met your rat race number through rental properties and want to get into realestate full time, how hard would it be to qualify for new mortgages after quitting your w2 job?

2.5x. That number isn't to be found anywhere in the Fannie or Freddie guidelines, and I arrived at it myself so it is unknown outside of the BP community. 

But if your net positive monthly rental income is 2.5x your personal housing expense, and all other non-mortgage consumer debts are paid off, once all the math is done then you will still qualify, assuming you're working with a local-to-your-state investor friendly loan originator who understands math and stuff. 

There are also non conventional loan products that you can qualify for.  Those options are more asset based and do not require the borrower to show income