hey I have not, it's like from the factory,
but I goving to Munich and visit the person who built my car, so I can ask him, I know he told me that one of the specialty stuff was that Gs used 2 springs per valve, so when the engine is running at 8000 rpm so it can even close to?,
Ther is a person named Jens Winter live in roskilde approximately 30 minutes from my home, he has raced in a 2800 BMW Alpina and many other cars such as the M1 Procar, he knew Gerhard Schneider and his technician and recer driver Dieter Basch, he told me that Gs engines were very strong and it should be according to him better. (do not know if he wont make me happy) He also said that gs tuning were sold to a racing team from Walter Brun.
He said they were beste to do fomel 2 engine