I'm looking to replace my speakers in my 05 WRX with a set of 6510cs and 5012is but have a couple of questions that I can't find the answers to.

My speakers haven't turned up yet so I just want to make sure that I've got everything to avoid the panic trip to Halfords with half the car in pieces. I'm getting the IAP adaptors to that bit is sorted but will I need any adaptors to connect the speakers to the existing wiring?

With the crossovers will I need extra wiring?

 

I got about 10m of wiring for the front speakers / Crossovers, and I also bought a selection of Spade connectors for the infiinty speakers, 'cos there seems to be about ten different types

 

Just had some Bostons fitted to my 05 Wrx.
Was going to do it myself, took the door card off stripped out the old speakers out, then after half hour of trying to decide what goes where and deciding how many trips to halfords for different connectors etc etc it was going to take.
Decided to let my local ice specialists install them for me 2 hrs later perfect job and great sounds.

 

Wire from HU to old woofer needs to be routed to new x-over, probably need to extend the wires (chock-block will do plus some extra 'speaker wire; x-over is probably screw terminals so maybe some crimp 'spade' (fork?) end types for this, otherwise just use bare ends of the wire).

Wire from old woofer to old tweeter (and old tweeter itself) can be binned.

New wire from x-over to new woofer needed, x-over end as above, small and larger crimped terminals needed on woofer itself.

Ditto for new tweeter.

I got a 'speaker install kit from Maplin, included wire and crimps etc - there are cheaper ways to do it but I was feeling lazy for this bit.

Do the fronts first as it'll make much more difference than the rears.