1. Glasswool + ported box = floor full of glasswool
2. Stuffing material + bandpass box = zero bass output.
Your only options are:
a. Placement. Moving the sub away from a wall can drop the bass output considerably, leading to less boom.
b. Equalisation. EQ can reduce the peaky output of a 4th order bandpass box like the one you have. The peak for such small woofers is usually in the 60-80Hz range, so some negative EQ (about 6db) with a parametric equaliser can even it out. Shoot for a Q of 1.5-1.8, a notch frequency of 65 Hz, and a null of about -6dB to tame the notch.
c. Level. Simply backing the sub level off will reduce the peakiness of the output. If your woofer does not have this control, then this option is not feasible. The MX5021 didn;t have it, but the Creative bass units all have a control for the sub level.