For me, I modded the intake for massive air, stage 2 hotcam, and a custom header. Then have it all dyno-tuned. I actually had my intake made via the dyno so I knew where my greatest power gains would be. I did the same with the header. The mechanic made several headers until he got the right bend for the most useable power. Dynos are great if they are used properly.
My next mod will be p-n-p with the valves being cnc machined and back cut.
Also, I am thinking about boring the carb bigger. I dont know if I can get a bigger carb in the space I have, so I am going to bore the stocker.
I am doing all these mods before I decide to bore it out. And right now, I am faster then several 480's out there anyway, because they havent modded it correctly.
Hope this helps.
2003 Houser CRF 450 Hybrid