blow off valve for golf 1.8t causes any problem?

Answer 1

well it will shut down the Turbo if it opens early or destroy it if it sticks shut ( at max boost - high rpm )

Answer 2

Many, many problems. It will warp your head, lower oil pressure, causes lifter noise, and erode your valve seats. You will also experience decreased fuel economy and increased drive train noise.

You would be better off taking up the game of golf (the topic of this category), which is a much better way to blow off pressure.