X-JET NOZZLE - DS TWISTX Jet nozzles have become very popular in recent years. These nozzles inject and proportion soaps, chemicals and liquids at high or low pressure without going through your machine's pump. For those of you into terminology, this method of chemical injection is referred to as "downstream injection" because the introduction of chemicals occurs AFTER the machine's pump. Downstream injection, in many cases, is preferred rather than "upstream injection"