The Oma/Grandma Kadett built by WKT, also known with his really fast White Opel Kadett with 900+Hp. He also built this one with around 680HP!

The Kadett was tested on the German Highway and had an unbelievable topspeed of 313km/h-194,5MPH. Watch the video below with his topspeed run.
https://youtu.be/EFsy9FH6tVw