My boxes are to spec, actually i have over the minimum size recommended. Plus it dampens the sounds of inside the box and lets you hear the bass more. Great if you are limited on space as i am.

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2003 Ford Ranger, 2.3, XLT Single cab
K&N Air Filter, 3 inch coil spacers with Add a Leaf, 31" Wild Country M/T,Chrome Wheels, Flowmaster 40 Series, 120" CB antenna, Cobra 380 CB, Custom Interior, Cab Lights, Tinted windows, Green HID kits, 2 Memphis 10's, Alpine V500 Amp, 4 Kenwood 6x9's, 600 watt Pioneer amp,Custom Camo Box, Blue, Green, Red and Pink leds. Custom Headliner, Explorer OHC, Autodim Rearview Mirror with Autolamps, Lighted Visors