I mounted it as low as I could so that I could get atleast 2 screws into the metal. I do have the power rear slider so I dont know if I loose more space back there or not. I will look through the pictures I took to see if there is a better shot of the exact position its mounted in.

Sarge

 

Maybe this one is better

 

That looks like my AMP..LOL
I mounted mine behind the right seat for easy access, where you mounted your AMP I have (2) 12" shallow subs in custom box.
I removed the Jack handle and tray so the Speaker Box sits low, reinstalled the seat with 1/2" clearance from the back of the seat.
Fits so tight my back seat will not fold all the way flat.
The Bass is really awesome hitting the back of the seat and the sound is directed down under the seat.
I was told from a stereo shop this can not be done, I showed them..

 

I was able to build a custom box and fit an Infinity Kappa 12 in mine and it sounds awesome! I actually need to remake the box about an 1" shallower so that I can fold back the back seat. Highly recommend a sub for any type of music

 

So you think I should be ok. If I get a sub, I may go with the thunderform which fits under the rear seat...which is why I didnt want to mount the amp there. If I cant do that I will go with the JL st up wich fits inside the center console.

Could you post up a pic. so I have an idea of what you have?

Sarge

 

If you can afford the JL i've heard great things about....I've actually heard really bad things abou the MTX sub enclosures thats why i didnt go that path. I have a visio diagram of my box that i built if you want? PM your email address and i can send it...I'll also try to get some pictures and i can send you those in time

 

I looked at the under the seat box, there is no clearance for the seat to fold down. The seat and the tray are almost flat with the floor, the only option is to go behind the rear seat.
I would take photos if my back seat would fold down, it is locked into the up position. The only seat that folds down is the right seat. The woofers are a shallow design, I forgot the brand, they are not name a brand I have heard of.

 

I agree the only way to go is to put it behind your seat. If you go with a 10" sub you'll have a lot easier luck building a custom box. My 12" sub has a mounting depth of 5" so its a little challenging (but i wanted some thump to my bass). If you just want a little bass an 8" bass tube behind the seat is always an option too. If anyone is interested in the dimensions for my box PM me you email and i'll send you the Visio doc of it.