Loss of rpm

[simonwg905]

07 215 wake
24hrs on clock, seen 7900-8050rpm when stock.
Added 3inch intake and intake grate & 14-19r ---7000rpm only but much better low to mid range.
Then put in wedge + RR wheel +riva washers + power pipe......WOT straight to 7000rpm then kept on wot 2-3 seconds later reached 7600rpm
So, how can I get those last 400ish rpm back?
Weather is hot in hk now!
Jerry, love all those parts from u, just need some help here about the lost rpm.
Thanks guys!
PS , I felt I lost a bit of lower end after power pipe installed, is this expected?

[DIGGS]

I Think The 14/19 Is Too Much Prop For A Stage I Wake

I Will Let The Rxt Guys Handle This One.