subaru - whining sound

spark plugs and subaru: don't get the high quality wires.
stupid plastic inserts AND the fact those spark plugs are so far in there it took alodia and I about 3 hours to get the plugs back in.
that aside, we started it up and it ran fine. then we noticed this high pitched sound that was pretty faint. hmm. wonder what that is. reved the engine a bit and by 2k rpms it was MUCH more pronounced. shut it all down, looked it over, and i'd failed to tighten a pully down (used to sinch up the belt to the air condition pump).
took it for a spin, sound great.
we'll give you a call tomarrow if we don't get to work in once peice. i'm pretty confident it's up to speed, but i've got this desire to pack my 3 toolboxes of tools with me, ya know, just to be safe.