I put Polk MOMO 6.5 components in the rear ledge....just made a bracket the fit them slightly below the ledge so the speaker movement dosen't hit the metal....and mounted the tweeters on the read ledge..they are directional so i feced them towards the front....and i mounted the crossovers on the back seats in the truck next to my CAPS.
they added a ****load of midbass...i'm not saying go spend 500.00 bucks on MOMO's but if you mount 3 8" subs in the rear deck with a nice Sony ES amp 300.00 bucks 75x4@0.5 OHM stable and bridge it to those 8" and tweeters and you will get some good bass..
3 8's in the rear ledge will be like a 10 in the truck only cleaner......and a lot more responsive to fast beats.....
just my thoughts tho....

Black 99 SE 2.5L MTX
17Inch TSW REVO (Silver)
225/40/17 Toyo (Z-Rated)
Energy Suspension Mounts
20% Tint (Sides and Rear)
Koni Adjustable Struts
H&R Springs
2.25 Exhaust
Dual Vortech Mufflers
Removed Resonator
Brospeed Tips
PIAA BMW Style Headlights
PIAA ION Blue Fog Lights
Smoked Blk. Side Markers
KKM Intake
BAT Air Inlet Pipe
Superchip
B&M Shifter
Kenwood P907 Touchscreen
4 10" JL Audio 10W3
900 Watt Kicker Impulse
40x4 Sony ES Amp w/EQ
4 Gauge Wire
2 Full Monster Farads
4 Clarions 5x7 2 Ways
6.5" w/ Tweeter Polk MOMO Crossover
Clifford Bullet 4 Alarm
Remote Windows
Remote Start
Tilt Sensor
Motion Sensor
Impact Sensor
BN White Guages w/ Blue