Nice looking numbers!
I was there as well (white F30 335i)... but couldn't get the transmission to stay in gear, as even in Sport+ & transmission in manual mode, it kept kicking down a gear. Tried in 4th, 5th, feathered the throttle until around 5.5k rpm, then floored it but it kept downshifting to a lower gear. Very odd. It was a green motor (just hit 700 miles), but even with the Power Kit + M Perf exhaust, I only ended up putting down 275 hp/281 lb-ft.
Does your X3 have the 8-speed ZF transmission?
2013 335i M Sport w/ PPK & MPE
Past: '12 335i, '11 Touareg, '10 X5 35d, '08 G37S, '06 330i, '04 330ci, '01 IS300, etc.