Mario,
I am no T4 expert by any means, but from what I have gathered here and on STF is that the bus 2.0 heads are the least desirable of all heads for performance T4 motors.
To start with they have very small valves (37 x 33) compared to (42 x 36) on 914 2.0 Heads & (41 x 34) on 1.8 T4 heads.
A stock 2.0 914 motor makes 95-100 hp depending on pistons used (flat or domed).
So you are better off finding a set of 2.0 or 1.8 914 heads, they are a much better starting point.
I hope this helps some...
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WinterJam 2010: Vdub, Surf, Skate & Musis Fest
WinterJam 2010
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