Rep Power: 0

So, I ordered a new cd player just 3 days ago, and it does not have a crossover, but I have factory components in the front, will I have to buy a crossover? (Alpine 9851, 04' Civic Coupe EX)

 
Rep Power: 0

no, it already has one that is 4 ohms. nothing to worry about.

 
Rep Power: 328

Just install as normal with the wiring harness and everyting will be fine. The tweeter is wired into the harness away from the HU, so you only have a right and left positive and negative wire for the front speakers to worry about.

 
Rep Power: 786

No crossover needed, just wire everything up and you are good to go

 
Rep Power: 786

for any future reference, the tweeter is wired into the harness inside the door