I don't think the CAI will work. I think short ram style intakes will work on both but the CAI goes down below through different places (again, I think...)
The Y8 head is better, should give you a few horses, whether or not it's worth the work and money is your call. The cam and valvetrain will work to nearly 7800rpm (I've been told) if you remove the rev limiter from your P28 ecu. Just chip it or something. The smaller chamber should give you theoretically .4 higher compression so you might get more power than you'd think just from that. But there's a little bit of porting that needs to be done in the intake tract on the Y8 for it to flow at that high RPM.
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