the one with the flange or without?
Is the sole purpose of the flange to mount a bov ?

 

What do you want the elbow for? I know of three variations. The standard-for looks and better airflow. The one with the BOV, and there's one in which you can mount an additional injector. If you are running really high boost, I'd go with the last one. If you are still under 15psi I'd go with the BOV version. Hope I helped a bit.

 

thanks