mvres

Is the stock brakes good enough for a 300whp s3 8l or should they be upgraded?
Not driving on track, just for daily driving.

bazzle

It makes no difference imo
If your doing a set speed, horsepower doesnt help slow you down, it just gets you up to speed quicker.
Now if you want to repeatedly stop quick etc then uprated components will help a lot.

BostonDMD S4/Allroad

Yes, stock will be fine for DD.
On a track, different story......