i was just wondering... on those 20B engines assembled with 13B, if ir were to be ran as an NA, they would have to use high compression rotors correct? would they also use housings from an NA (6-port), or can the turbo housings be used also (4-port)?

since the JDM 20B comes with turbo, they should have low compression rotors right?

 

You can use any 13B rotors in the 20B engine, regardless of compression. It would be better off to get the higher compression ones just to make that much more power. You can use the stock 20B housings for an NA application as well.
Basically, unless you want to throw in the high compression rotors, you could just strip off the turbocharger system and not touch the internals and have an NA 20B.

 

by using rotors of lower compression for NA application, the power would not be as high as it should?

 

Correct.