It does have speaker mounts and I use them. However, I tend to use the speakers in them at low levels as they are really close to my ears and, therefore, can easily dominate the sound. So they are best used as rear channels and at low levels.
But overall I really like the Highliner. It gave me a place to neatly mount the GMRS radio as well as the altimeter, and gets compliments frequently.
Gary, AKA "Gary fellow":
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Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI