3/4 is perfect, just make sure it is sealed well with lots of glue and screws.

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Soon to be gear:
Amp: Alpine MRP 450 MONO
Subs Two Pioneer TS-W307D2/D4----12"
Box 1 cu ft/chamber sealed
Deck pionner DEH P6800
Front spks 5.25 kenwoods
Rear spks 6x9 pioneer 3 ways
caps Raptor 1 farad
Wiring Streetwires 4 gauge wiring kit
Battery Interstate
Alarm viper 2 way

some mismatched brands but lots of good gear coming together