I was taking apart the top end of a zuma that exploded, when I got a load of the head on it. I was like damn, thats gotta give better compression than a spree head. Its like, there are three concentric circles inside, almost like a double squish or something. We have already established that hondas, at least hobbits and expresses, have the same bolt pattern and bore/stroke as the newer minarelli horizontal style scooters. My second express build, express II, is ready for a new head, and I think this is it. Check it.
My, and most peoples, major quarrel with the spree head is its lack of cooling fins. I have no prob running them on stock expresses, but kitted ones I wouldn't. If you look, the zuma head, on the left, has thinner and taller and longer cooling fins than the spree head in the middle.
Here you can sort of see what I mean as far as three rings inside the dome. Never seen a head like it. Anyway, its going on express II tamary, and we will see what kind of compression/performance gain I see. I feel like the cooling fin area is about equal to the stock head, but the air can't get through to the cylinders fins as easily. We shall see what happens.