Well Dakota I can say the old bikes fire up faster, as far as power not so sure if it is in my head or is a fact,
but does appear to pull a little better.
Just put a set in the F-150 2 days ago, time will tell, I don't normally track my MPG, so can't give you that stat.
My 3 friends and co-workers that have them say they noticed improved performance and MPG.
Some say it is snake oil type BS, so I suppose you may just have to try them and form you own opinion.
I figured it was worth the try in the bikes as only needed 2 in the CX and 4 for the GL.
Hope this helps.