How do I find the engine code on a Subaru Impreza?

I went to purchase spark plug wires for a Impreza rs.
I was told that there are two types of wires available and have to know the engine code so that they sell me the right wires.
where can I find this code?

under your bonnet on the back firewall, there will be a metal silver rectangle, this will have your paint code aswell as month and year of make, it'll have your engine code. On some cars, the compliance plate the small, silver rectangle, may also be on the inside of your drivers side door.

last job was in spare parts and Auto merchandise.

call your local dealer give them the vin # and they'll give you the information you need.