[stackj]

It really depends on the people in your local FSDO. A good number of the inspectors will accept a change (Field Approval) that the manufacturer considers an improvement.

Some inspectors may require that you have a DER go over the requested change and bless it off.

Some inspectors won't approve any changes. I think your best bet is to arm yourself with documentation on the old system and the new system and go talk to the inspector about it... find out what their requirements are.

Good luck.