HKS Extension kit for GT-R & Skyline GT-R

Since the genuine extension merges the main passage and the bypass passage with the turbine, when the actuator is activated, the main exhaust flow and the bypass flow interfere, causing the secondary exhaust pressure to rise and the exhaust pressure to rise temporarily. It will rise, the boost pressure will drop, and it will lead to power down.
The "extension kit" was developed to eliminate this useless power reduction and bring out the full potential of the turbine.

For more details please go through the below link...
HKS Extension kit for GT-R & Skyline GT-R