With the Twin Injector Pro Kit of full kit set, you can install fuel system when in high power tuning.
You can put the desired size of injector for your need at secondary side.
They are attachment type.
Standard attachment is for stock injector.
The injector hole of surge tank is closed at the shipping point, so you can use it with single injector when you are not using the twin injector pro kit.
HKS: Twin Injector PRO Kit for GTR35 High Flow Surge Tank
Brand: HKS
Part Number: 14007-AN004
Stock images used. Actual product may vary.