No harm at all with different size filters. The only difference you will find is the sound it makes more than likely. I wouldn't claim the bigger filter to free up any extra horsepower than the smaller one either.
Iv used a 6 inch...9inch...and 14 inch filter and have seen 0 diff in readings and or power......only diff was the bigger filters had a little more sound to em
Iv used a 6 inch...9inch...and 14 inch filter and have seen 0 diff in readings and or power......only diff was the bigger filters had a little more sound to em