For your headunit I would strongly recommend you get a simple good headunit rather then get stuck in the complications of a separate processor controlled headunit. Keep the setup simple and sweet. For the headunit you can reserve 15k like Musti mentioned or get a good used one (Kenwood) from a fellow PW'er. Contact him and he might come down if you are interested. Kenwood x7013u is perfect.
Link: https://www.pakwheels.com/forums/car-audio-video-electronics/234352-high-end-sq-head-units-sale
For components I would recommend good components since your front stage is very important. Try getting hands on Focal Access A1 or Infinity Reference CS6030. Otherwise Mubeen bhai if interested in the soundstream components, let me know. They are very sweet sounding and have no shrill or fatigue on your ear.
Link: https://www.pakwheels.com/forums/car-audio-video-electronics/235625-audio-bargain-sale-hertz-soundstream
For amplifier get a 4ch one so that you can put your rear stage on them too in future if you plan to upgrade to them. If you want to get 2ch then Muneeb has Focal Solid 2 for a great price. It is enough to power your front stage with decent SQ. For 4ch I would recommend Pioneer GM6500F otherwise. Cost would be around 10k for a new one.
Link: https://www.pakwheels.com/forums/car-audio-video-electronics/235321-fs-audio-euipment-subs-amps-rca
For rear stage check out whats available in the local stores nearby and get decent coaxials for the rear shelf isntall in civic. I would recommend focal if genuine are in your reach otherwise JBL or whatever suits your listening preferences
For subwoofer sell this out and get a JBL GT-5 or atleast a JBL1202/1204/1212/1214 whichever is accessible for good lows. Put it in a sealed enclosure and run it on a suitable mono.
For mono get a powerful 2ch enough to run a sub on bridged mode. For that krieger is the person to approach.
Overall this will cost you 54k with adding everything and reducing price of Kenwood sub.
working: 14+8+10+6+5+2+8+4-3