Here's a more sceptical view of it from The Daily Green:
http://www.thedailygreen.com/l...61008
I tend to agree with the Daily Green writer that the claims are very dubious based on too small numbers and the real-world testimonies are really not verifiable. As far as we know, they could have been written by Blade employees in the break room. The comment by the reader after the article admits that maintaining his tire pressure and changing driving habits may well have accounted for the small mpg improvement on his Honda.
As for reducing the carbon footprint by putting a filter on the exhaust, I'm sure you can find a much cheaper exhaust filter than $200 for a Blade.