DA90 CREW WAS FLYING THE SNA NOISE ABATEMENT PROC AND WAS GIVEN A LOWER LEVELOFF ALT.

Narrative

TKOF WAS FROM RWY 19R AT SNA WITH AN INITIAL ALT ASSIGNED OF 5000 FT MSL. WHILE USING NOISE ABATEMENT CLBOUT PROCS; TWR CHANGED OUR LEVELOFF ALT TO 2000 FT MSL. THIS OCCURRED WHILE USING MAX TKOF PWR; PASSING 1100 FT MSL AND CLBING AT 4000 FPM. WE RESET THE ALT ALERTER TO 2000 FT; BUT THE FLT COMPUTER HAD ALREADY PASSED ITS CAPTURE POINT AND RENDERED THE COMMAND BARS USELESS. WE OVERSHOT OUR ALT BY 200 FT (2200 FT MSL). THE REASON FOR THE CHANGE WAS A VFR ACFT AT 2500 FT MSL. WE REALIZE THE CHANGE WAS FOR OUR SAFETY. HOWEVER; A 30 SECOND DELAY IN OUR TKOF CLRNC OR BETTER COORD WITH SOCAL WOULD HAVE SAVED THIS OCCURRENCE. SNA WANTS NOISE ABATEMENT TO WORK AND THEY ARE SERIOUS WITH THEIR FINES AND OPERATING SUSPENSIONS. HOWEVER; THE TWR AND APCH CTL FOLKS NEED TO RIDE THROUGH A COUPLE OF THESE TKOFS IN A HIGH PERFORMANCE ACFT TO SEE WHAT A SUDDEN LEVELOFF DOES TO THE CREW AND PAX. A BETTER REALIZATION MIGHT SPACE THE TKOFS A LITTLE TO HELP OUT. WE'LL DO OUR BEST NOT TO HAVE THIS HAPPEN AGAIN.