Well the old friend google and search function wasn't much of a friend on this one, so maybe you guys can help.

I found a rebuild kit for the Hitachi HT-18 turbo, but I am unsure if it is any different between S4 and S5. I know that they had different turbine housings for the twin-scroll and independent twin-scroll, but would that effect what rebuild kit you would use?

Also, trailing from the turbo itself, when switching to the independent twin-scroll turbine housing, does the S5 manifold have to be used as well? I am assuming it does, as the flange on the housing has a different shape, but one should always be cautious right?

edit: I did just find RotaryRocket's thread on rebuilding it into a hyrbid, so that may answer some of my questions. But if you've got nothing better to do, then feel free to post

 

manifold has to match the turbo series, so S4 manifold will not bolt up to S5 turbo.

both S4 and S5 use the same rebuild kit, standard T3 with 1 piece carbon compressor seal

 

Different size waste gate as well.

 

The wastegate is completely different from S4 to S5. S5 has a twin compared to the sinlge 16mm of the S4.