[2turboimports]

If you're going to take out the piston you'll need to make that cylinder where the piston slap was uniform at least, so you'll probably end up needing a slight bore/hone/whatever. If that's the case, most machine shops I've dealt w/ charge 2 times for 'mounting the engine' in the machine since the block is in 2 halves. All 3 times I've over bored a subaru engine, it has cost ~$350, which doesnt leave much room for pistons, rings, gaskets, any other misc stuff if you're aiming for a $500 limit.

Anyhow, the stock valve clearance (same for N/A 2.2 and 2.5):

Intake (mm) - - - .20 +\- .02

Exhaust (mm) - - - .25 +\- .02