Is it okay to vent a sealed sub box yourself?

I have a 12" kicker comp woofer in a completely enclosed (sealed) sub box and I want to manually cut out a vent hole on one side to release air and get more bass (in my small car). I know that the comp woofers aren't deep to begin with but the box I have it in is about 1 1/2' deep so I got room to work with. Any reasons why this wouldnt be smart?