HKS is a little late to the FK8 downpipe game but in doing so they were able to create an optimal design for their ecosystem of parts.
The 2-piece downpipe and front pipe combo use the same layout of the factory parts and are connected in the middle near the engine roll stopper. This layout paired with the front pipe's flex pipe ensures no leaks or cracks in the exhaust system (something the early 1-piece downpipes were seeing).
The HKS downpipe was also designed for power so it removes both Catalytic converters. Therefore, this product is for OFF-Road use only... so now that formalities are out of the way.
The downpipe has a smooth 3-inch design and it follows through the front pipe where it tapers to 2.55-inch to match the Legamax or Spec-L cat-backs. While this sounds unimpressive to some, HKS wanted to ensure proper back-pressure for their parts. While a full 3-inch design might be best for high power applications, HKS knows that most drivers will be using bolt-ons and this design is optimized for just that.