I have run the two speed weights but only in my mod Polaris, not in my Tapex. Played with them a fair amount and first impressions were favourable. It felt sronger on the bottom and would pull well through the top end. After many drag races though it was always proven the polaris weights would out perform them. Yes i know there are a multitude of variables always involved. Trying to compare as fair as i could the 2 speeds would not pull as well as polaris weights. I also suffered a major failure in the 2 speeds when they came apart and shrapnel everywhere. This was on the first version, i heard they are much stronger now. Still have these along with my billet HCX collecting dust. Wouldn't reccommend them from my experience.