Couple things to note. That downpipe is made for a 3 bolt exh housing for your turbo. Unless your racing in a class that requires it. I would get a 4 bolt turbo with a external gate. It opens your target audience to more then just Buick guys when time comes to upgrade and the 4 bolt tan housing with a V-band clamp are better for sealing it with no pesky exh leaks round the housing, not to mention that you can fit a bigger exh wheel in a 4bolt housing then you could in a 3 bolt which will obviously make more power.
With that being said, I bought the same downpipe. It comes with the downpipe, adapter that bolts to the 3bolt exh housing and a V-band clamp. Because I opted for the 4 bolt turbo, I went to a chassis shop and had them fab up my system. They cut the V-band portion off of the adapter, and welded it to my existing V-band on my 4 bolt exh housing so I can bolt up this downpipe to my turbo. They then added the flange portion for my wastegate to my header, then routed it back into the downpipe.
By them doing this, I have changed the entire configeration of my downpipe. It doesn't run like a normal downpipe should. Meaning my 4"RJC exhaust had to be modified as well to line up and work properly. I have a lot of room to work with seeing as how I don't have a heater box in my car. If you retain the heater/AC I would advise you to keep to a 3 bolt turbo for exact fitting, because this downpipe is a super tight fit in the stock configeration.
Attached is the finished product of custom fabbing it to work with a 4bolt turbo.
