I run 15 to redline too - pretty wicked eh?
what boost do you see at part throttle around 3-3.5k?
You wanna be carefull around there as your car will want to boost straight to 15, and if you aren't WOT you'll be running way way lean. I held it at around 3500 rpm for a few seconds part throttle and I got mad compressor surge, the car went into convulsions from the various PCM cut-outs, it snap/crackle/popped, etc.. It actually didn't do this until I put my new exhaust on - the combination of quicker spooling and leaning out the AFR had a big effect (and I'm not stage 1). It's definately time for me to upgrade my fuel system (FPR, return line, eManage). then it's hopefully 20 to redline
