So reviving this as I was having the same issue myself with APR tune with 1.8 IS20, EPC when trying to rev out past 6000 RPM. VERY, VERY long story short, I came up with a solution after pulling what little hair I have out. Although some have resolved their issues with plugs, and coils, etc, my mods are in my signature, fresh step colder RS7 plugs gapped to .024 I just couldn't fix it either. It seems like enough of a universal problem with those of us with the 09G that you would think that someone other than Ian@Reflect could do an "09G compatible tune".
Without further ado, the solution for me was to stack with a JB4 and create a custom boost curve in Map 6, no other changes, just the new boost curve *with a taper off up top starting after 5500 RPM*. These are my logs where I simply taper the boost down starting at 5500 RPM. To me that's literally the solution for my car. It even feels pretty smooth without running out of breath as timing takes over more when the tune sees low boost up top. I did start with 91 octane w/aftermarket DP but used a 2nd out of 3 included reflashes for free to downgrade to their lowest 87 w/stock DP tune and it was still an issue until I did the custom boost curve. Now, gonna go back to the 91 but with stock DP so I get more timing back for low end response but w/stock DP option it keeps the boost a little more safe to work with and still very decent power peaking at about 23-24psi on 91.
I must add, as part of the process I contacted APR support and without using these words myself, only describing the problem, THEY even said it was likely "transmission torque limit". Now that I have found a fix, I don't want to have to live with a JB4 connected all the time to fix a bad tune for an 09G when I shouldn't have to, so I'm hoping they will offer me an adjusted tune or I get my money back and it goes to Ian, who I'm sure will work with me on a custom curve that works for me.
Full-ish pull -
datazap.me | danbfree | Torque limits fixed, just needs boost taper up top.
3rd into 4th "Punch it Chewy" -
datazap.me | danbfree | Boost fixed 3rd-4th punch
I may still have a bit more in 'er too, this is just what I am at for now, tired of burning $5 gas up for the moment.