MAPerformance, or whatever it is, made just about 400 on a dynojet with an hta and e85. I think that was at either 26 or 28 psi. JSarv made just over 400 on an airboy plot with a regular 18g and e85 right before his car got totaled. I believe that was a 28-29 psi run with front mount, and he had previously been making 360-370ish on an sti tmic and (I think) 26ish psi. That was with an 8cm exhaust housing, which made more hp over the 7cm throughout his entire rpm range.
Really, the stock ej205 heads/cams aren't designed to make a lot of top end. Pretty much any setup is going to taper a bit up top, unless you're running such a big turbo that it's not fully spooling until almost redline.