Are you taking into account the sides of this exo chassis that will be higher than the floor of the chassis when you are insisting it will raise cog? The exo chassis spreads the weight over the entire area of the chassis whereas the plastic chassis with weight under the saddles should be more centrally located and maybe a little forward biased. I would have to see the proof to believe the cog would be raised. To get a fair comparison on plastic versus aluminum they would have to be run back to back on the same truck , not two different trucks. JWhiting, lol.