I have t61 .81ar on cast manifold with VPC afc2 set to about 11.5A/F at 18psi. Someone said that it's not safe to run more than 15psi for longer highway pulls; I’m talking about 170mph+, simply staying in it till 6th gear. I have always turned the boost down to 1bar as soon as I hit about 140mph because of that reason. But if I tuned the car for 11.5a/f at 18psi and than turn the boost down to 1 bar and running rich and the car looses a lot of HP. So what would you say is SAFE boost. Also my EGT shows about 750-800C max at 18psi pull. I also have FJO to monitor the A.F.