Pay down home Mortgage early ?

[Steven Schreifels]

I am a newer Real Estate Investor with goal of purchasing first rental property by Sept of this year (my next B-Day). I've just refinanced my primary residence from 4.7% to 2.8%. As before I plan on making bigger payments (about $150 more per month) to be applied towards principle. Was wondering if this extra money would be better saved towards 2nd rental property (will be using an old IRA to fund my 1st rental property) ?