I have a series 2 engine in my S1, the ony remaining series 1 part is the coil packs, because the igniter on S1 is mounted on the coil cover on S1, and S2 have a different ECU which ignites the coils. If you can avoid it do NOT use the S2 turbo, I am advised they can not stand BOOST, they have a PLASTIC/SINTHETIC blade/impellor, I am advised not much good. If you are changing you ECU you can use the S2 coils, so long as the new computer is S2 compatable.