First a quick background.
Had the car for over 2 years, around about 18months ago my car had a new clutch slave cylinder fitted and since then i noticed the annoying over revving when changing gear. not so bad back then but a year later it started getting really bad. change at about 4k rpm and it would shoot straight up to 6krpm.
Car - Audi S3 2001 facelift
Jabba custom map before i bought the car
not alot else done to it.
So i replaced the clutch switch (the one on it was broken anyway. - didnt cure the over revving
Replaced a N75 valve from another S3 which didnt have the problem - didnt cure it
removed and cleaned TB then re-aligned - didnt cure it
replaced the DV with a forge one. - didnt cure it
But yesterday, i was checking the car over, checked the brake fluid res, rear left under the bonnet as if you are standing in front of the car. Noticed a rubber pipe directly above it which runs alongside my charge pipe had split, well gone brittle and cracked where it connects to a 90 degree bend. At the time all the garages had closed and i needed a quick fix to get me where i was going. so i used duct tape, taped the crack and the connecter so nothing leaked, plus a cable tie to make sure. - well this seems to of cured the over revving while changing gears. drove for around 350miles the past 2 days and its been great, it still does it very slightly but heared that remapped S3s so it slightly anyway to keep the turbo spinning.
so anyone who has this annoying issue check your rubber pipes around the brake fluid res and see if you have any split.