Cisco ASA5510 Bandwidth Shaping/Limiting
Solution 1:
This:
shape average 9000000 36096
actually gives your ASA license to burst the the bandwidth you've allocated, if there#s been a suitably quiet period. If you want a guarantee that you never exceed a given bandwidth, using policing is a better option (on the other hand, with policing, any packets that exceed the bandwidth will be dropped instead of delayed).
Solution 2:
Unfortunately, I don't have an ASA to check/test with but I use the below command on one of my routers to limit the bandwidth to 6Mb. Perhaps something similar will help with your shape question.
interface Serial1/0
rate-limit input 6000000 112500 225000 conform-action set-prec-continue 0 exceed-action drop
rate-limit output 6000000 112500 225000 conform-action transmit exceed-action drop