i did bring my own no prob. and do check the first page about the 10k km service.

Have answered it before in Shawie tered, please refer below:
Since you're wondering, so here's a video for you. I purposely drag my daughter to conduct this experiment for you, at the same time I can educate her



Can you see the difference? With and without swirl. However, those bits that use to twist the air flow were meant for noise absorbency, therefore at the same time you're getting a better noise reduction(which is not exactly what you want ). If you want loud noise, just remove the centre bullet, go and twist a pipe and weld it on Last but not least, the rear tip weld a trumpet tip your exhaust sound will be amplified together with the swirl flow, next time before you reach roadblock the fuzz ady waiting to collect ady