What is a wastegate (bypass valve) and what do you need it for?
Turbocharger Wastegate and Engine Performance
SRP TURBO T3/T4 External Wastegate – Japanese Race Supplies
A-Premium Complete Turbo Turbocharger Kit, with Wastegate Actuator, Compatible with Caterpillar for CAT C12 & Detroit Diesel Truck Series 60, 12.7L ...