I’m not finding anything for upgraded ignition for a 2003 seems like the 2001 is readily available but not the 03.
Nigel it definetly had more power than a 125. The problem was that there was no top end. If you look at the power curve for an 03 it hits around 46 HP @ 8000 RPM after that it really falls off. I never messed with the OEM Mikuni carb so maybe it could have been dialed in and made better but the Air Striker was much better even before it was jetted. I ended up with a 180 main 55 pilot clip in mid position. Between that and the rad valve it really woke up the top end. Now it’s considerably faster than a 125 but not as fast as the CRF450.