External Wastegate

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Senior Member
Ok, i'm going to turbo my Z6. I am going T3, and aparently the flange that I need to buy to bolt up a downpipe (or even aftermarket downpipe) will block off the internal wastegate. This kind of pisses me off, but i guess it's the only way (if it's not please tell me how i can still use the internal wastegate). So i have done research on external wastegates, but I do not know where they bolt up to. Do they go before, or after the turbo? I'm very confused. Some pictures or someshit would be very helpful. I don't know jack about external wastegates, only internal. Thanks for your support! I'm sure this post will get many bullshit comments other than answering my question, but if not, then you are my bestest new friend! :D
External wastegates install BEFORE the turbine section. They do essentially the same thing as your internal setup, they just divert exhaust gasses from ever entering the exhaust housing rather than simply diverting them around the turbine wheel (but having all flow still go through the housing). Here's a pic of an exhaust manifold with provisions for mounting an external wastegate (notice flange)...


The only complication with an external wastegate is that they need their own exhaust pipe to be street legal, which is usually merged back into the main pipe somewhere downstream of the turbo's exhaust outlet.