All E46 M3s will have the 3.2 liter S54 inline-six, which produces 333 hp. so, your source was incorrectin that respect. However, if i remember correctly, 2003 was the year that the M3 was given a 7900rpm redline instead of the 8000rpm redline. the problem was that people had been running them up to 8000 and kept blowing the engines, which BMW had to replace under warranty.