sub box for '06 Sierra Denali (crew cab)

[Kali Denali]

Hi guys,

I'm trying to find a subwoofer enclosure for behind the rear seat in my crew cab sierra. I'd really like to fit one 12" sub back there. The best I could find online was an enclosure for two 10" subs. A guy at a local stereo shop said you can't fit a 12" sub back there. Is this true? There's got to be some way to fit a 12" sub somewhere in the cab of this truck. Can anyone help me out?

Thanks

[lerbud]

subthump makes a downfire box for a denali that goes under the seat for 10" woofers. i had a box behind my seat and it sounded like crap. the downfire sounds 100 times better.