same as running a 3.4, 3.2 without a tune... Sure you can, you can buy a new engine too!
After I did my 3.4" swap I ran the car for a week on a stock tune... Didn't hurt it at all. Didn't even knock much. Tunes are only REALLY needed when you start making changes like injectors, MAFs, Gears, stuff like that. A tune at any time can help though.
97 GTP Sold-prolly rusted away by now
2011 F-150 Yote powered
Too Hot to Handle, Too Cold to Hold