[danielo]

The closed loop capability on the stock ECU is what wrecks havoc for piggyback tuning.

What options are there to disable it other than a reflash or the DP ECU?

 

[bstar360]

Have a look at this post by someone else.
I don't know if its correct I'm not making any claim here.

The ECU reflash claims to disable the O2 sensors and that stops the fuel correction ability of the ECU that would happen during closed loop operation. so if the tune trim file was made with 0% ethanol then I would need more fuel right off the bat over here.