im curious exactly what this does. is it better to buy a h/e or go with a dual pass?

 

Dude, search a little. There are tons of threads on this topic.

In brief:

Dual pass provides more direct cooling at the manifold where it counts, usually lowering IAT2's by about 10 degrees on average.

H/E adds additional capacity and cooling ability to the system to prevent heat soak and control temperatures better.

They both work well, and work better when combined. PM me when you are ready for a dual-pass plate.

Joe