I put a thread up a while back about a service where I'd also had an RR session showing my power rising well up to about 4,500 then tailing off reaching a bit of a plateau.
I could feel it in the car too. Basically holding the car in gear and increasing the revs but the power didn't seem to be there.
Well .... the recommendation from the tuner and a guy on here was to replace the map sensor.
Today, I replaced the map sensor and the power vis with a recon unit my father-in-law did a while back. I was unsure if the unit from the car was defective but thought I'd change it anyway. I've not taken the cover off it, but it was pretty oily under there.
Just got back in after about 20 miles. Took the first 10 steady to ensure the car was running OK and picked it up a bit. Last couple of miles were very progressive and all I can say ...... Awesome !
Pulls strongly all the way now to the red-line and feels really better - much smoother delivery. When the exhaust gets sorted I expect it to be absolutely bang on.
The proof will be another session on the RR. Can't wait.