Thermometer Stem Length

I am considering adding grate level (3" face bi-metal) thermometers to my smoker door, one close to the firebox and one just before the chimney. I can get either 2.5" or 4" stems.

Will the performance (accuracy) improve appreciably with the longer stem? If not I will select the 2.5" which will provide more room for Q.

This is going on an Old Country Brazos (Academy's heavy one) and the cooking chamber is aprox 19".

Thanks!

Great,
Thanks so much! I will go with the shorter stem to keep the chamber space open.
Randy