are you referring to a cultus or Alto vxr? In either case, the wiring loom is present in the car. They are simply not connected since there are no speakers in the rear doors.
Usually, it's a good idea to buy aftermarket speakers since they will sound better than the stock speakers. However, if you want the same stock speakers, I have a pair that I removed from my vxl when I was upgrading my setup. They are mint and will be a plug & play in the factory wiring harness. Let me know if you want those