As far as I know the "power blade" marketed in the UK is exactly the same as the "power now" in the US. If you do a search on power now you should find all you need to know, I have seen some good ideas on how to make your own on DRN, it does seem a lot of money for a bit metal.
I made one-i wasnt convinced it was what they say-i think on part throttle it was good or better than std, but on full throttle it seemed to hold back on overrev.I took it out and didnt feel a great difference.It seemd to make the bike crisper in the mid however.