normally i could answer this question but either half the junk put in my truck is not mine, then it is, and inbetween all that the trucks broken so much i havent been able to tell yet. i would assume you wouldnt be able to tell because the crawl box is in high just like the back case. its basically neutral not doing anything.
that was my reasoning as well...it should be no more than parasitic loss. But I swear you can feel a difference. Maybe it's all mental. the thing to do would be to have an unbiased driver (read: honda guy) drive it before and after.