dang where are you looking? most i see are over 5"

 

Mtx has a 10 that is under 5, kicker 10s seem to be just over 5

 

Mtx and kicker

 

Im stuck between JL W1's and Kicker CVR's. Some sites will tell the xmax under specs

 

Most anything your going to be able to fit under your trucks seat will have less than 15mm of xmax. Also, xmax is described as the amount of travel before the voice coil leaves the gap, and includes rearward travel. So even if you have a sub with 15mm of xmax, you would probably only need 10mm to clear the forward travel of the sub.

 

I'm not too picky on the brand, I would just like to be able to fit them under my seat without modifying anything

 

Good to know, I haven't been able to find the xmax specs for any yet. Just trying to find what speakers I can use to fit them, box, and account for xmax within 6"

 

Honestly if you gave your sub 1 inch of clearance it will never touch the seat. Doesn't matter what sub it is. And personally for small enclosures JBL makes some decently priced woofers, I've heard them and was pretty shocked with the amout of output.

 

so in that case, am i going to be able to find a sub that with the thickness of the box, will be 5" thick?

 

If your just looking for some extra bass and not an earth shaking system you can get some rockford shallow mount 10s for pretty cheap. They are the rockford prime series. You could also probably get away with 1/2 inch MDF wood for your enclosure. That will also help keeping the height down.