Replacing Speakers - Keep the same wiring?

[Conor D]

I've just got the JVC door speakers, and headrest speakers from MX5Parts.. At the minute I only have one set of the headrest ones. To install these, can I just keep the same wiring that's there and connect up the new speakers or to I have to rewire them to the head unit at a certain Ohm or anything?

If I install the one set of Headrest speakers, again will this need any modification to the wiring or should they not cause any issues. The new JVC headrests are rated at 4 Ohms, and the door speakers are too.

Also, If I later put in an Amplifier, where in the chain does it go.. and again, would it require new speaker cables or will the stock ones be able to handle the load?

[Conor D]

Just tackled the headrest speakers there, found out the old speakers were rated 4ohm too so no problem. I'm guessing the door speakers are the same story.

Now, the amplifier?

[MX-5 Lazza]

When I replace speakers I always run new wires but to be honest, without an amp the standard wires are probably adequate.
If you fit an amp you will need new wires anyway though. The head unit will supply a feed (RCA input hopefully) to the amp (which can be fitted anywhere you can find a space, mine is stuch to the bulkhead carpet behind the drivers seat with Velcro) and new speaker wires will run from the amp to the doors.

I've never been keen on headrest speakers myself. IMO they just ruin any chance of decent sound as it should come from in front of you.