Because the data logger measures airspeed using static pressure, and the size of the opening on the sensor is fixed, if you change the size of the pitot intake you'll either have to recalibrate the sensor or live with the fact that your airspeed readings will only be "IAS" (indicated airspeed), not "TAS" (true airspeed).
FYI - IAS is measured from the difference in dynamic and static pressure, if done properly. Dynamic pressure is what is being "rammed" into the front of a pitot probe. Static is a reference, based on your absolute pressure. If you are saying that the size (diameter) of your pitot probe inlet makes a difference, then that is an incorrect statement. Pressure is pressure as far as the dynamic pressure goes, as long as the system has no leaks. Doesn't matter if you have a 1" or .10" hole there. Odds are that you'll see huge errors by not having the static port outside of the fuselage. The best way to measure is via combined pitot-static probe setup.
Michael