We can program a FS2 HHO chip for your 1997 Chevy Blazer. That is what we usually recommend, however some of the best gains we have heard of are from the EFIE and MAP Sensor Enhnancer Combos.
Every vehicle is different. The FS2 HHO Chip is very easy to install and if you don't cut the wires, there is a 30 day money back guarantee.