Turbo replacement on a 2004 passat

I'm going to assume you have a stock 1.8t. if yes.. the turbo is located between the block and the firewall. easiest way to find it's exact location is to follow the piping from your side mount intercooler. replacing it will take some time, i've seen it done on gti and the removed the engine because of limited space, so you might have to do the same. I'm not sure on the amount of space under the hood of your passat. I hope that helps.

nope

if its the 1.8t the turbo is called k03 and you can find it on ebay or anywere else but if you want to modify it there many websited and they usually put the k04 turbo