The obx header eliminates at least one cat.
If you're looking for more torque lower down, take a look at their dyno sheet before you buy. You may find the 4/1 adds little, if any, kick at the bottom end/midrange and pushes everything into the upper mids and high end.
A 4-tube equal-length shorty tuned header usually adds lower end and midrange grunt without sacrificing top end ability.
A 4/2/1 will add upper midrange twist and provide better scavenging into the higher rev range.
A 4/1 is designed for all-out racing where higher revs are needed with other mods to provide max output.
This header usually costs you at the bottom and into the midrange.
Each is designed for specific results based on intended use. (burnout)