You have one external amplifier for the subs and roughly 25W/channel for the rest of the speakers. If you want boom, you'll have boom but if you want balanced sound, you need a separate amplifier for the rest, then balance the sound once it's operating.
Guessing at the crossover settings won't get you where you want to be- use an RTA program or app and find out what the speakers can do and look at the system response first, then tailor it to what you want to hear. Hopefully, your goal isn't just to have a loud car. You seem to have chosen crossover frequencies used for home theater- don't, unless it just happens to work. You're dealing with a vehicle that will have road noise- use an RTA app on your smart phone (the mic in iPhones tend to be more consistent than in Androids) to measure the noise without the system and set the HP for the fronts at the upper end. You could set the HP for the 6x9s a bit lower, but since you're not using them for deep bass, it's not as important that they dig deeper- they'll be needed for the mid-bass. Start with the LP for the subs in the 60Hz-80Hz range and eliminate any peaks that show up- tone controls should be set flat without the Loudness button engaged.
Setting the levels correctly- this is where a lot of people get into trouble- without seeing the signal, it's almost impossible to know when the head unit, speakers or amplifier are distorting and don't let anyone say "I just use my ears". One way to set the baseline for the levels:
Do the level setting for the head unit several times with each song if you have never listened closely for distortion- it's much easier to hear distortion at low levels than when it's blasting.
1- Choose songs that have wideband sound that's not already distorted and has a fairly high average volume level
2- Decrease the input level setting for all channels to minimum, or close to it
3- Play the music during the louder passages and increase the head unit's volume setting to roughly 70%, listening for distortion in bass notes, vocals, synthesizers and drums. Find other songs and repeat this step, making note of the volume setting when it starts to distort.
4- Use hearing protection for setting the amplifier level controls for the reason I posted above. Set the balance/fader so ONLY one channel is playing- once you hear distortion, decrease the level control and play the other songs making sure the channel isn't distorting. Once you're done, set the balance/fader to the next channel and repeat this for each channel.
5- After the input sensitivity for the main channels has been set, increase the level for the sub channels until it's slightly higher than the others
while all channels are playing - it's doubtful that you'll need to use all of the amplifier's power for the subs, but it's good to have headroom.
6- Get someone else to drive and go for a drive on roads and highways, to look for and listen for gaps and peaks in the response- make notes and take screen shots so you'll have visible information. Adjust as needed and repeat the road tests.
Make sure to use adequate power cable gauge- if you don't, your amp won't deliver, it could overheat and you'll probably have some kind of noise in the system. Go to
www.the12volt.com for wire gauge charts. Add a heavier wire where the body is grounded to the battery- that skinny wire will never pass the current your system will try to use and it will prevent all kinds of problems.
Remove the door panels before cutting anything. I looked at a 2000 Impala door panel- looks like you won't need to cut anything.
