No more benefit

Hello, normally I’m just a hard-working reader here in the forum, but today I also have a problem. I am enthusiastic owner of a 9-5 SC Automatic Hirsch Performance (EZ 10/2007, 48000 km). Had the opportunity yesterday again and wanted to give the deer the spores…… Unfortunately the deer didn’t want to do so. So far I was used to the fact that the vehicle turns into the 5th gear at full acceleration at 225 km/h, continues full to 240 km/h and then slightly slower Turbo indicator was until then always in the middle in the red area. Yesterday from 200km/h only little of it could be felt, from 220km/h there was practically no acceleration. Turbo indicator up to 200km/h middle red area, after that only to the red area. In normal operation I have so far not been able to detect any change to the vehicle, the vehicle is driven mainly in urban traffic, daily way to the job 13km, little stop and go. Sleep the horse n over time if they are not constantly demanded? Does anyone have any idea where the problem might lie? Thanks for your answers. kles