dont waste your money on new pistons if the old or good, unless you are going with forged. The stock are better than 99.9% of the aftermarket crap.

Thats a 16g you are talking abut not a 16a. I'd go with the evo3/big 16g if you are going to get one. Make sure you get the td05h wheel and a bored stock exhaust housing. It's a pretty fun turbo but it isnt very efficient at 12lbs. I'd bump it up to 14 or 15. They were designed to run around 18-24lbs. Might want to look at a 17c 19c or 14b also depending on what kind of power you are going for.

Get a better radiator, bsek, chrome and molly rings, throttle body rebuild kit with the throttle shaft seals. walbro gsl 392 fuel pump if you plan on pushing that turbo what so ever. The stock ones are not too bad but they ar epretty tired after 25 or so years. I hear mk2 supra fuel pumps flow real good and are external as well.

I havent tried this yet, but im pretty sure the second gen monteros should have a oil cooler that is a upgrade over the stock starion. Seem to be quite a bit taller than a starion. Might be worth checking into.