yes I have got positves results with this kit in very standard conditions, just bolt on with a Simo pipe and a 122 jet on a 24/24, (much, much better then Malossi just bolt on with no other mod. ) up to more complex set up with special lip long stroke crank and reed block.
I personally never had major problem with one of this kit if properly fit and timed, but considering the reports from competent people I know, it seams that one on ten can give you problems, in the same way Mazzucchelli race crank can one in a ten.
I found this kit to be very sensitive to the head you are using so try, if you can, two of them of different shapes.
For example in a longstroke version the use of a Worb5 head made for longstroke with a squish of 2,5mm (to use with no head gasket) the difference with a MMW head with the head gasket was as noticeble as going from standard stroke to longstroke.
And I agree with Diablo. I would love one of this made as it should have since the beggining. If I had money I would order a special production in alu from gilardoni with a special piston…
maybe SIP one day could order a Polini 208 Special edition…
I think they would sell them all even at double price the actual kit is.
The new Grand Sport piston it seams just half way through the right path.