So my 03 wrx has no motor. I'm not sure where to start with as far as should I go with a used 2.5 motor or try to get a long block. Advice would be great
I might recommend seeing if you can get your hands on one of the new FA20's from the BRZ/FR-S/2015 WRX. From what I hear they're much easier to tune and a little more reliable once tuned. Though, there's not a lot of empirical data since the engine isn't that old. Oil filter on the top is really cool though; and definitely makes oil changes easier. I loved the convenience when I had an FR-S and miss it with my STi.
I've got an 06 I'm parting out. Couple blocks and heads too. I you wanted the chassis harness and ecu to run single avcs I could make a sweet deal. Blocks are in pieces, and built as are the heads. you're on your own for headers and turbo, unless you want to go bawls out and then you can have my garage.