box tuning for alpine type R

[sdg0080]

okay so i've got an alpine type r 1242d....

i am building a box but am trying to calculate the tuning Hz. in the owners manual it gives these specs on a 1.7cuft gross. F3, ripple, Fb (33Hz, +2.5Db, 36Hz) so my question is do i tune to 33Hz the F3 or to the Fb of 36Hz. so i am confused as to what to tune to. normally i've always tuned to the F3 is that correct or do i need to tune to Fb?

thanks.