Cheers guys. Current N75 is the E variant, which is the latest revision for this car. Supplied by SERE.
So yesterday I managed to do some logging and adjustments using the SPS switch (thanks Yohan
). Haven't had time to sit and go through the logs properly, was at the pub for the Grand National yesterday and too hungover today
Basically, we ended up pulling back the boost to 5 which reduced the noise and flat spot on boost in 4th. After logging CFs we pulled timing back to 3 to reduce correction factors. So we were thinking that maybe boost and timing settings of 6 and 4 respectively were a bit too aggressive for my car.
On the way home I noticed though that I still have the noises and slight flat spot at WOT from lowish RPM in 3rd though. So not sure what that means in terms of what's causing this. I'm sort of thinking possibly a boost or vac leak somewhere, Yohan commented that the lambda figures looked a bit wobbly.
Will go through the logs and graph some of the data tomorrow and see what's what.