yes you can look into shallow mount subs like RE Audio,jl,etc.....
what ever you do keep your amp,
jl isnt for every one.
i like the slash amps, & w6v2 line as well w7's
when it comes mostly down to speakers & subs it all about box,placement,aimoing, porting, sealed, yes it can get complicated at times, you need to learn how to use gear your before buying more.
on your amp what are your settings?
filter mode?-------------------------------try it off or low
filter slope? 12 or 24db-----------------i like 24, but you can play with 12 or 24
filter ferquency/xover?------------------ look around 65/80
input sens?--------------------------------go about 1/2 way, then you can adjust it less or more to you liking
output polarity? 0-180 phase----------play with phase,yes it can make difference
infrasonic filter?---------------------------when you have a ported box you sometimes get port noise, the filter help stop that noise.but it can take hurt more then help @ times,
what is your setting on your deck???
do you have a xover on the deck,eq,bass filters??
play with it first to see if you can make it sound good.
you can learn how to built a box,
if you go to homedepot in the back where they cut the wood for you they have scraps of wood that they sell for like $0.57 to $1.20 a piece,
I'm still learning how to make the best box for my car,
i've made anbout 10 different boxes for my hatch which i haven't been pleased with yet, i'm working on a new now,
car audio is like a drug an expensive drug that you can learn from & have so much fun playing with.