I have tried baking at a higher temperature (175°C/350°F/Gas Mark 4), but found that the granola started to burn around the edges around the 20 minute mark. The pecans in particular were borderline burnt, and I found the that 165°C/325°F/Gas Mark 3 worked better. That being said, every oven is different. You can give it a try at 175°C/350°F/Gas Mark 4 and see if the higher temperature works better for you. You may need to reduce the bake time.