Finally got dyno results and now I want more!!

Da Flash

Well, I got my Z dyno'd about a month ago and here is what I got on a Dynojet;

Z1 CAI, Berk HFC's and OEM Nismo CBE before tune;

285 hp/238 tq

After tune;

301 hp/ 251 tq.

The first thing that I noticed was that my N/A turbo lag was basically gone. I had to relearn how to drive the car! Definitely an improvement in hp and tq but, I was hoping for something more in the 320 hp range.
The tuner suggested long tube headers as, he claimed that one of my HFC's was restricting flow limiting him to 27 degrees of timing instead of the typical 30 and that that would open things up. He also suggested a better flowing/LOUDER CBE. I'm not really feeling louder as I'm getting too old for all of that. I have read that the LTH install can be challenging and may only net me 8-10 hp so, just looking to you guys on what I could do to get to get me to the 320+ hp range. I was thinking of E85 also.