So learning more about car audio little by little, and I always like to tweak my stuff to the best it can be. I read a little bit about polyfill and how it simulates a larger box by slowing down bass waves. I tried it once before, but i remember it really seemed to decrease my spl and some of the bass notes just didn't sound right to me so I took it out. However, this was back when I was a noob and had my gains set wrong and my bass boost way up. I've now got good amps that are set right so kind of want to experiment again. Current set up is 10" kicker cvx powered by alpine mrp-450 pushing 400 watts at 2 ohms. It is in a slit ported enclosure and I think its max size it can take (1.75 cu ft.) but not sure. I'll need to measure to confirm. So i love the sub, box and amp combo and it hits hard for a 10. Guy at my local car audio shop thought it could hit 130's. I'm becoming more of a sound quality guy than spl and been really interested in box designs. Not looking to spend the money and have a custom box built just yet, but ive been hearing a big sealed enclosure sounds way better than ported. Would like to try a sealed sometime, but how does a ported sound with polyfill? How much should I add? If my box is built to max volume the sub can handle is polyfill needed? Will it hurt the sub? How damaging is constantly taking out and putting back in a sub to the box? Should I drill into the same screw holes or put in different ones?