HKS' original sound control technology created the "Slotted Tail" design.
The "Slotted Tail" was inspired by an owl's feather. The owl's feather-shaped exhaust tip has an advanced silencing effect. Releasing adequate air from the tail can reduce the air friction vibration which enables the sound to be reduced by approximately 2dB. HKS conducted intensive analysis of the sound level and frequency inside the vehicle's cabin and outside the vehicle. Therefore, the best exhaust tone was tuned for both inside and outside the vehicle. Also, the low frequency was eliminated to present more comfortable sound.