Car audio systems. How much is too much?

[Snapman007]

I need some help, or therapy if you ask the one with sense.
A few months back I ripped the factory sat/Nav out to update the GPS and gain iPod/iPad connectivity, DVDs and music Bluetooth etc. I went to to shop and ended up with anAlpine 7" that does what I wanted it to to do.
They threw in in some mid splits for the front and back plus an amp to run them and an invoice for 31. A few weeks later I realise I'm not happy with the imaging and sound stage. I'm now comparing it to my home system which is the problem. I wasn't "very" unhappy with the factory system but obviously had issues and we didn't use it.
I was back at the shop today and got a price to add sound deadening and extra insulation, upgrade the speakers and amps plus ad 2 x 12" ultimos with amps and new front speakers, crossovers, tuning etc
My plan is to remove the amps and speakers when I change vehicle so they are a long time purchase. We only travel 10-15k a year in this vehicle. It doesn't get used on the weekend locally.
I'm interested to hear from people with big arse systems that do big k's to justify the misses shin kicking me to the back of the head"
I'm conditioned to part with some good dollars on both home and car audio systems.

[D4D]

I used to spend $$$ on 'hi-fi' gear back in the day when the source input was good quality vinyl and even CD's that weren't tuned or compressed. These days the music you buy is low fidelity and compressed hence I don't bother spending big $$$ on lo-fi gear.

[plusnq]

I used to spend $$$ on 'hi-fi' gear back in the day when the source input was good quality vinyl and even CD's that weren't tuned or compressed. These days the music you buy is low fidelity and compressed hence I don't bother spending big $$$ on lo-fi gear.

X2 plus the listening environment isn't exactly optimal

[Snapman007]

These are the two main reasons I'm hesitant. It's a lot of dollars if I don't get the result I'm chasing.

With my home system it's almost impossible to enjoy anything downloaded which is 90% of what gets played in the car.