how many decibals are you you guys hitting with your Fi BTL 18"

Your not going to get what your looking for.

Every setup is different and WILL return different numbers, so don't expect to be able to guesstimate what "your setup" will do.

Anything between 110 and 194 dB is possible.

Are you trying to guesstimate your setups numbers or just curious what people are doing with their setups? If you explained a little more, people might be more receptive. Have you metered yours? What are you doing, and with what specs(ie. box size, ported?, vehicle, power)

.....lol been here...done this.....these people wont tell you what they hit bro...they will just tell you every setup is diff...and never tell there db. rating....they dont understand you are not asking about your setup but theirs...

its like training pitbull or other bully beed dogs here....they are thick headed......i have a buddy that hits 153.7 on music with one btl 18...hope this helps...your setup will be diff tho