Try automating the cutoff of a Low Pass Filter.-APZX
I find Pro Default is usually the best with pads or vocals, but I always try out the other methods just to be sure. For example, that loop in your project is 133 BPM and ...
The time stretching is changing the tempo of the loop to fit with the project. But if you mean changing the tempo of the loop itself, so it will play at the new te...