I have an omex ECU and apparently that couldn't run the vvti as designed ie. gradual changing of the valve pitch, but rather either full on or off if that makes sense.
I also lost the FBW in the process as well. I guess this means that before the turbo kicks in at 3800 revs, I haven't much power as I could have, but as I tend to drop down for any attack, I don't experience issues as I prefer to drive around 6 mpg
My only problems arise on idle. I was told this could be rectified with a larger throttle valve but as my knowledge is limited to just opening the bonnet and topping up fluids, I have decided to live with it. This does mean that as I come to a stop I have to be concious to let the revs die down to around a 1000 before putting the clutch in as if I do it earlier, the revs dip to such an extreme that it stalls.
The lesson I guess is if you are going to buy a Supe that you intend turning into a single, then don't buy a vvti tiptronic until the gurus have worked out all the solutions!
Sorry I can't offer any more help.