Didn't feel like reading 16 pages but I was told from a buy building boosted motors for 30 years that turbos require 0 backpressure. Not saying he is right, just what I heard.
Also, I have yet to say this here but I hate how 4 and 6 cyl engines sound. A V8 is nice and an inline 8 is amazing sounding. Of course there are also the classics like a small displacement Ferrari V12. But an inline 4? can't stand it.