Alright, I gave the calibration a try, seems to have helped. I could slightly feel it on occasion but it was far less abrupt. I think now I'll have to wait and see once I can get a tank full of 93 in there and see how it acts. That will also give the computer some more time to adjust I suppose as well. Thanks guys
It may have been causing a full boost partial throttle situation. In most turbo cars this results in one of three/four things.
1) Dump lots of fuel into the cylinder to prevent detonation and reduce knock by using the increased fuel supply to pull heat out of the charge air. This usually feels like a bit of a power drop as you don't have enough air to go with if it is working. IF that doesn't reduce knock sufficiently then...
2) Pull ignition timing really hard. Which feels like a serious power drop. IF that doesn't work then...
3) Fuel cut! Turn off the injectors, because no fuel means no detonation. No detonation means your pistons live to see another day. At least in the cars I experienced this in, it was usually at uhh... highway speeds... yeah that's a suitable description.. in significantly cold weather. It feels like your car hit something without all the screaming and crunchy noises.
Newer cars may try to avoid doing number 1 for economy and emissions reasons. Newer cars also often have variable boost control which can be applied as step 0 or replace 1 - 3. It's reasonably graceful and non-violent but is a definite power loss. However, it is less likely to be effective with small turbos as they tend to suffer more from boost creep and can wind up with the wastegate being the primary boost limiter under a number of relatively common situations.
Also a weak wastegate actuator means that your wastegate may be limiting your boots to a lower PSI/bar than intended by the engineers.
For the 1.4 turbo, given the max boost specified in the documentation on it vs. what people playing with them in other vehicles claim to be the observed behavior regarding max boost, I would say that the small turbo is indeed prone to boost creep as is common with smaller turbos due to packaging issues, or because they put a small turbo on a larger displacement engine for the size of the turbo to reduce boost lag. boost creep doesn't suck power per se. It's just an efficiency issue and heats things up resulting in 1-3 above. Boost modulation doesn't help as much with it because it is a symptom of the wastegate not being sized properly unless it is a symptom of the car's boost controller having bad software, being mis-adjusted, or just generally sucking.
