View Full Version : 2008 Chevy Silverado Ext. Cab Install Help! Under Back Seats

08-05-2011, 06:34 PM
I have a 2008 Chevy Silverado extended cab and I want to add some subs to it. My top choice would be the kicker 12" L7's, but if I cannot create enough space under the seats I will switch to different ones. I Just want a lot of loud bass. I was wondering if anybody could help me on trying to build a box to fit 2 L7's under the back seats. If that is not possible, I found this box on subthump.com that fits 2 12" shallow mounts. I wanted to know what the loudest shallow 12"s are. here is the dimensions for the box: Mounting Depth: 4.5", Volume: .65 cu.ft ea. Sealed Box, separated chambers

Replies Welcome!

09-13-2011, 08:59 PM
Not sure why no one replied to help. This was posted over a month ago, so not even sure if you are still lurking on the message board or not. I have the Subthump deep box for 2 12's in my 2008 GMC Sierra crew cab. The 12" box will fit up to 6.5" of mounting depth. I went with two RE SE 12's. It sounded pretty dang good. Extended lows and the sound quality was great. You only get .83 cu ft of airspace before sub displacement so I was leaning towards the minimum box space recommendations, so I know they needed more airspace. I could tell they wanted more airspace just from the sound. With the windows rolled up and at full tilt, it sounded pretty crappy to be honest. I'm sure with more space, it would have sounded better with the windows up. Im honestly wondering if I should have went with two RE SE 10's instead of the 12's with the amount of airspace.

You don't have to go with shallow mount 12's. Alot of subwoofers fit this description. The RE SE 12's are pretty beefy subs. I am looking into switching my system up with doing some SA-8's ported. I know I can fit 2-3 SA8's ported, but I am doing some research and box measurements to see if I can fit more. I am having a tough time justifying going from two nice 12's sealed to 2 8's ported. I'd really like to see if I can squeeze in 4 or 6 of the SA-8's. That would be something ridiculous. After doing some measurements under my seat, I came up with 2.92 cuft of airspace before sub displacement, which is .05 cu ft and port displacement, so I really only have enough airspace for 4 of the SA-8's at .73 cu ft of airspace, before displacement.

Hopefully this will give you some insight on doing some 10's, 12's and maybe think outside of the box and doing some 8's. 3 8's have the same amount of cone surface area as 2 12's and you can go ported, which will be louder and depending on your tuning frequency, dive down lower.

09-13-2011, 09:40 PM
2" spacers under the rear seat mounts gives much more space to work with

09-17-2011, 05:45 PM
allright you should probally just go with 1 nice 12" so you dont have to take out the seats and people can still sit in the back, the box is going to be 22" long the base plates are each 11". you have to space raise the second plate from the first 2" so you can get over the framework. you have 6" of room way in the backand keep in mind under the seat is not hard. the width should probally be 17.5" and bring the wood up at the angle of the seat, then at the end of the seat have a 5" piece of wood angling upward so you can get the max amount of space on the front of the box. the sub will be firing towards the back of your seat. depending on how big you make the base plate you can probally get 18" of space. I made mine 12.5" and had a 6"plate under it for my 10" Bl.

ive been working on my box back there all day. hopefully this helps

Bettr n' Revrse
09-17-2011, 06:01 PM
Didnt we just go through this?

09-17-2011, 06:50 PM
I think we went through this with a member who was trying to do the same thing with his F-150