Chris:
Juan's question was whether the Enya must be reworked "like is done on the OS engines". My point is that many here recommend that no reworking at all be done on an LA 46, the FP 20, or the LA 25*.
I don't consider restricting the venturi a bit to be reworking -- just tuning.
* There's even two schools of thought on the LA 40, one being that it Absolutely Positively Must Be Reworked, and another, smaller one, that points out that the original LA 40S came with a humongous venturi and it works fine with the right prop and a smaller venturi opening. I can't say anything about that -- I own a reworked LA 40 that I love, and that pretty much worked right out of the box for me, but I don't have an unreworked one to compare it to.