There is a s5 turbo forsale localy. I was thinking of getting it as I know the s5 turbo has 2 wastegate ports and fight boost creep alittle better.

What I was curious is can you just put the s5 turbo on the s4 TII? I know the downpipe is the same but didnt know about oil lines and the exhaust flanges.
I searched but couldnt really come up with any answers. I read some people were talking about swaping the exhaust manifold so I wouldnt have the twin scroll also.

 

You need the S5 exhaust manifold, turbo & downpipe gasket.

The S4 oil/coolant lines swap over, but the heatshields don't. You can cut them to fit partially. You may be able to get away with an S4 DP gasket, but the S5 has a groove in it, and you may develop an exhaust leak.

Also, definitely port the wastegate before it gets bolted on. Take the openings as large as they'll go without going past the area the door covers.