I used this Garrett-based setup for 5k miles with an eBay "churbo" t3/t4 turbo and a Garrett t3/t4 turbo, both with Stage III (3) turbine wheels on my Miata. The Mercedes 5-bolt wastegate housing has a contoured wall that smooths the exhaust flow from the wastegate port to the exit vs. the typical flat-face of most internal wastegate housings. There are no flaws in the turbine and wastegate housing- all threads are clean and usable. Downpipe is designed for a top mount turbo manifold and is built from schedule 40 gas pipe. The entry matches the 2-½" exit at the wastegate housing then immediately steps up to 3" and ends with a standard 3" collector flange. The downpipe also includes a bracket/boss for an assembly support arm. USPS flat rate shipping $18.