Running out of puff

In second the car should really fly into the limiter, and trust me when it does it feels like you've hit a wall.

I've started running the car on super-unleaded again and it seems to have helped it, but it's still dropping a bit of power over 5000.

it will do by the time you are in third if accelerating from rest. it will be even worse if you have been going uphill as the turbo will have been on boost and hot for even longer. it's that "heat saturation" problem.

I put a temp sensor "in" the pipe between the intercooler and the V6 plenum. it is up to 70 degs in third, 40-50 degs higher than at cruising speed. This is about 35bhp, about 20%, just lost to the heat.

Cruise in top, then drop it down to 3rd and you will feel the real power as the heat saturation has not taken it's full grip.