*I posted this in the Stereo General section but thought it was more useful here*

I have a GMC Sierra Denali Crew Cab truck, and the 10's I installed were lacking in the lows department. Additionally, it didn't have a whole lot of bass, and I wanted more. However, I did not want to do a "blow through" -or- "bed cut". I also did not want to remove any of my seats, nor alter the seat in any way.

Older Silverado's and Sierra's had lift kits for the rear seat, but nobody has made one for the NNBS 07+ seats yet, so I thought one up. I am using all steel, with "Grade 8" hardware, so it should be as strong as the original. Also you have to raise the seat-belt buckles up as far as the seat so they still work.

I had read elsewhere that guys were cutting 2 3/4" off of the back brackets, to be able to fold the back down, so I figured I had at least that much to work with. I also don't sit well with every single post reading similar to this, "The biggest you can get in there is 2 10's, and small one's at that." Or, "Small 12's will fit, but starve for air, so just buy smaller subs." PFFFFF!

I got ahold of some Rockford Fosgate T1 12" subwoofers, and wanted to make them fit. Mounting depth is 6.625", but I will have more than enough room. Box should net around 3 ft^3, with enough room to keep them from hitting the floor.

I went to Lowe's, and bought these materials:

10 (Grade 8) 1/2" x 1" bolts
10 (Grade 8) Nuts to go with them
10 (Grade 8) Lockwashers
50 7/16 hole big face washers
6' 1 1/2" square tubing
Misc thick square "washers", these were just for look, but this could be accomplished with regular washers too.

Here is where we are so far, will be done tomorrow or the next with pictures to follow.

Subs:



Materials:



Seats Out (To show where the mounts are):





Finished Brackets / "Lift Blocks":

 

OK so here are the rest of the pictures through to the final product. The seats are as strong as they ever were, just lost some head room, but still comfy. I am 5'9", and fit pretty good back there, but anything above probably 6'2", might have some issues.

I raised the seatbelts so they are all still functional. Also I had to disconnect the cable going from the back of the seat, to the base because it kept hanging up on my amp. It really served no purpose other han to keep the seat back from folding forward.

I got the unintended bonus of having the ability now to fold them down if I ever had too. The seats also fold up, but I don't see a need, as I can get to my amp, and my jack, through the top now.

It turned out great, and even with the legs, I was able to get 3.1 ft^3 out of it. The low response is awesome, and way more than I expected out of a sealed box.

I say if you are debating this, take a swing. With a little thought anything is possible. Here are the pictures of everything as it was completed.

Finished Lift Brackets (also note the seat belt lift):








Space under the seat now!!! (10 3/4" at the front and middle):




Box:




Seat backs come down, and the hooks latch and keep tight when they are in the normal position, and I can get to the amp for adjustments:



Finished product!!!:

 

Overall, very doable, and plenty of space to work with. The 2.5" legs keep the subwoofer from contacting the floor, and as previously stated, the lows are great. Not much sacrifice, nothing crazy or permanent, and got the desired effect. Thanks for looking, and I hope this helps people looking to also do this.

 

Great info,I had never though of this,I had to cut the bed,but I went BIG bass ,3 13W7's.

 

Good job! I will probably be doing this in the near future!

 

1. Awesome write-up.
2. Great pics.
3. Don't let the back seat passengers wear cowboy hats and you're good to go.

 

I have 2 12"s kenwood kfc-xw1200. Shallow mount speakers. And they sound awesome. It's got a kenwood 1200 class D mono block. It fits under the seat fine n has mire bass than allot of cars around here!

 

By here I mean my area, but I agree good write up

 

Pretty cool must sound great ill have to admitt my trucks stock speakers in my 09 gmc have pretty good bass for stock but a cool system would be even better.

 

I couldn't do it. It would make me cry, and I have that bed locker there. It would've had to be a bandpass box to work.

That's why I made this!


My passengers shouldn't have cowboy hats, but I think that would be a stipulation to sitting in the back of this. They would just have to take it off, and I don't know the rules to that...

The small subs I had under there didn't hit lows worth a damn. Shallow subs don't have enough suspension to get the lows out the way I like. The bottom line is what sounds good to you though. Although I will say, even when I had my others, friends with similar trucks would compliment on it all the time.

The only way I ride!