With a big single turbo I'm out of fuel at 551hp. Without a lockup switch that number might be slightly low due to the limited RPM range available to spool such a large turbo. My truck defuels pretty bad over about 3100 too. Apparently TST did do anything about that. Another issue that will have to be addressed is the speed limiter (well for racers anyway). My truck feels like it hits a wall at 105-106mph. I think the '03-'04 might have 110mph before it defuels badly but none of us are immune. With twins and a lockup switch I can probably get to 600hp but I think that is about as high as is possible with the stock cp3 on #2.