it was a mystery to me too.... When I first got my lum, I had done a full tune-up, and I was just sittin' there, kinda revvin' the engine, enjoying the sound. But everytime it would hit 3000 it would hit a wall and fall. So I called a buddy of mine, who has owned nothing but luminas since man walked the earth (let him tell it), and he confirmed it, there is a limit. Sometime ago, while searching the j/y for a chip, i grabbed a 3.1 chip and put it into my 3.4. For some strange reason, it will let the engine rev to 4000 rpm, though it idled really crappy.