Actually if you measure the size ratio between the original clips and the encoded clips, the bitrates is actually less than what it should be.. It is because, I have not implemented the fillbits module.. The part when the bits buffer exceeds its maximum size. The extra bits is just discarded.
As for BWP, I don't really think it is very efficient.. I have not try out the LTP though.. BWP is disabled in a lot of cases such as when there is block switching, PNS and Intensity.. In fact I have some doubts about integrating BWP with MS Stereo! There is some theoritical calculations that indicate potential trouble in the use of BWP with MS Stereo..
Never tried BWP though in my encoder (actually I did in Psytel - but that was ages ago) - since it imposes problems with seeking and it is not commercially viable (i.e. - no commercial VLSI/DSP decoder will use that) - and the theoritcal gain is anyway very small