Replacement chain tensioner at 120 HP Cooper

Moin, occasionally our Mini Cooper R56 with the 120 HP engine is nailing at the cold start in the morning. Chain tensioner costs not 25€ and I wanted to change it. Especially with the Turbo there seems to be a lot of problems. I have found instructions so far only for the Turbo. Did today the air filter system with ours down and the hoses. I see the 27er screw. Only I can get no nut on it, let alone the one turned out. The throttle valve is in the way. If yes, what to consider when dismantling? Are these only the 2 Torx screws? Please short info. Thank you