[B33M3R]

Thanks

On the 'Base' system the mid's in the doors and under seats are on the same front channels in parallel. If you are looking to power the under seats separately you need to unplug them from the front channels and run new speaker wires to these, from an amp etc.

Technic sells custom cables with the correct plugs that fit into the under seats, if you are keeping the OE under seats but just amping separately, this makes things easy.

If you are replacing the speakers with something else, SWS8's, Jenherts, SSMB8's etc. you don't need these cables as the connection to the after market speakers will not need the OE plug. You can use any suitable gauge speaker wire.

Unless you are going to run new speaker wires to power the front mid's, for example using Technics harness, you will need to bridge the OE under seat plugs which powered the under seats, that are now left not connected to anything.

The jumpers sit in those plugs, bridging that circuit, allowing the mid's to work with the under seats not connected.

Does that help?