Not sure yet since I haven't done any A-B-A testing, but it has definitely helped cut down on the amount of tailgaters in my rear view mirror! Apparently the giant ecomodder decal was too subtle to get the message across, but they all get the message now.
They see the new decal and around they go!
I'm at 77.0 and climbing on the FCD on this tank at 295 miles, so it isn't hurting