Trust me, I'm all for builds. I did a full build on a block and kept up with the new bikes...For 6 months till the next new bike came out and i got blown away in brkaing, power, handling, etc. What sucks was looking at the bill I could have had the new bike. It's good our sport is still growing quickly, but it's kind of like computers. After 3-4 years why upgrade? It's time for a replacement if you want the latest/greatest. Just a fact of life with fast moving industries, sports, hobbies, etc...
You don't have to spend 10k vs 6k obviously. Your bike's gotta be worth 6000+, the BMWs are available for 10k all day long. 4k and you'll have better technology all the way around to match the massive horsepower increase.
Just let KWS do the head and tune, then put on some better brake pads and have at it for 2500$ or so. I am very brand loyal I will not jump on what is the next best thing. I will make mine better until Yamaha has the next thing on top. But that is just me. And for track use what is wrong with the new R1s? For a head up drag race yes the new R1 will lose. Plus I have seen 20hp increase alone with head work and a good full exhaust from KWS.
03 R1 SOLD
06 R1 Too Fast for you
04 Yamaha blaster 240 kit (kids)
07 YZ 250
02 YZ 125 (kids)
03 TRX 90 (kids)
07 KX 65 (kids)
I douvbt you will run with the bmws is thing thing. The electronics, chassis, etc you still won't have. You'll probably be close and MAYBE be with them, but they will still probably beat you unless you do traction control, quickshifter, etc. You're chasing something and about to pay much more and probably not even get there, just close. Also remember with the bmw you'll have a warranty and going this route you'll lose reliability and have no warranty. there is a chance in a year or two you'll need to rebuild it again.