I am needing to get rid of my granitelli MAF and go back to stock, so i am going to buy a stock on and put it on the car, the car when i bought it only had the granitelli. But i have heard some things about speed density, and i was just wondering what that was

 

It tunes the car based on the VE table and MAP sensor letting you completely delete the MAF. It's supposed to be very beneficial for people running cams, as its easier to get low rpm surging to a minimum w/o the MAF throwing things off all the time.
I'm going to be tuning my car SD here in the next couple weeks.