I wrote a script to compute the correct inspiral range based on a transfer function measurement using Pcal to CAL-DELTAL_EXTERNAL. I used a recent measurement (see LHO aLOG 46530) to test this script. 

In summary, based on this measurement, the correct inspiral range (if Pcal is indeed considered the true value), then the inspiral range is 89.3 Mpc. By comparison, the original computed inspiral range was 85.3 Mpc.

The script is stored here:
$CALSVN/trunk/Common/pyDARM/correct_bns_range.py

The important caveats are:
1) the installed front end inverse sensing filter must be the same as the model file/function that you are using, and you have to point the script to this parameter file (meaning you have to know what was used to install the front end inverse sensing filters)
2) while one can put any GPS time to get a DARM spectrum, the correction is really only valid near the time of the Pcal to DARM sweep
3) the transfer function and coherence data from the DTT template has to be exported to ASCII files

I attach two figures to illustrate this code on the recent measurement link above.
1) The transfer function data between Pcal and CAL-DELTAL_EXTERNAL to measure the correction needed
2) 4-panel plot showing the correction to the DARM spectrum