16v head, pistons. oil pump. Mega squirt EFI . Like a ton. But you need to be well experienced in engine work.
I am curently building a 16v/aba. Stock aba pistons bottom end. New rings for turbo. ARP head studs. Passat 16V head oil pump. 1.8T manifold welded to 16v lower mani intake. t3/t4 super43 trim . Corrado fuel injector seats. 1,8t fuel rail.
it's alot. you could get 200+ with a home made turbo kit running C2 software.
But the motor is only good for up to 300 maybe. the 16v will go way farther but it's up to you how much headache you want to deal with. The motor is a lot cheaper than a 20V an makes alot more power.