My 1st tune I put down 390ish range, but i went to Fastech's dyno and put down 376rwhp I was pissed cause my 224 cam put down 378 rwhp. Later after my retune I found out i had way to much timing in it and my fuel pump was working overtime. Retune at Fastech got me 392rwhp on there dyno, and they told me my fuel pump was dropping pressure at the higher RPMS. Might wanna check your timing and see what you fuel pressure is doing at higher rpms?