I found that the golf was cutting back on power at about 4.5k rpm for some reason, it had me scratching my head for a while as it was fine before taking it off the road.
my first thoughts were the turbo, originally the forge actuator diaphragm was leaking causing the turbo to overboost and the ecu cut power really early.
i fixed that and still had issues at about 4.5k so i did some logs which shows there was a lot of knock, particulaly worse on cylinder 3. this let me to believe that it was an EGT related issue.
calculating the mafs grams/second worked out it was pushing 205 bhp which was about 19bhp down from my RR results 224bhp.
I realised that the exhaust was restricted and i was running a stage 2 map. I had my standard cat fitted for mot reasons and soon realised that this was causing the restriction. So, i spent half an hour under the car and swapped over the cat for a decat and then did two more logs but this time i did them seperatly to give a more accurate reading.
note the mafs peak g/s in the plot below, if you calculated it to estimated bhp it works out to about 235bhp.
it just goes to show how massively restricted the standard cat actually is. there is a 30bhp difference without any tuning involved, apart from the newer turbo which hasnt yet been dailled in.
below is a log of the knock retard channels, you can now see that the knock has gone
the car is now driving freely to redline, though i never really drive to redline as i find there is never any need to as most of the power is mid range.