whats the difference, and what brand are RH?

 

a race header does not have a cat and a regular header does so the race header is illegal to drive on the street it for off road use only

 

Also, especially on the EP3/DC5, race headers can be made in a pretty different configuration compared to the stock "shorty" header. With the catalytic convertor out of the way, the extra space allows for some creativity.

Of course, that's apart from the JDM 4-2-1 header/cat combo. That's probably the only 4-2-1 design you'll find that can be street legal.