My ROTO on the tuned CF pipe (Ed Skoerpa ESComposites) really works.
I set it up for good response in 8000 9000 range.
This still provides nice throttle up from lower rpms .
You simply MUST put together your setup -on a proper bench and try prop pipe combos and listen to response at various points in the power band -right from idle.
This is not a "bolt on and go" deal.
Or copy some one elses setup then wonder why it doesn't work for you.
It is a concept of power tuning you must learn to work with - correct prop -needle setting heat - etc..