Help! with prius modifications!

Check this link for your audio information:
Prius JBL Audio system response, specs, and photos

I'd skip over the capacitor. The Prius power system will be able to handle your amp's power demands. It's just another device that sucks up power from the electrical system.

 

I'd be very careful about installing under lighting. It's illegal here in Indiana and they DO ticket people who use it. Besides, the Prius is pretty low to the ground with not much room for additional underpinnings due to the aerodynamics.

Besides, you can't be dazzled by the lighting if you can't see it. Instead of the outside, go for the inside. That way, you'll be happy and you'll avoid the seizure-inducing strobe lights in your rear view mirror.

 

There is plenty of room on the underside recesses to put lights without losing clearance. You don't have to see the lights if you just want that cool underbody glow at night. Very cooler on rainy nights (although still illegal in some places). I use mirrors or panels of mylar at car shows.

 

so you have the JBL?

you'll need a low pass filter. (can't recall the proper name) This sub install will require you to tap into the lines that feed your jbl amp so you can pull off the R and L signals along with the IGN On signal. the Speaker L and R signals (rear) will feed your low pass filter so your sub can be hooked up. don't try to hook up the speakers directly to the sub amp.. the jbl amp tends to get mad.

As Efusco said ( good man)... you're connections are all in the right rear of the hatch. the motorcycle sized battery is the one you are looking for.

if you need the wiring diagrams or other info, please do a google search under priuschat or a search in priuschat.. as this subject has been covered many times. (except the LED one) but that's simple... if you can get the wiring into the car...