I got one of each sitting in front of me waiting to be put in my FC. I've searched a lot of atmospheric vs recirculating threads. Most of it is preference. However, I notice some people say a recirculating bypass valve has more benefits as far as "precharging" the turbo.

My question is: Hypothetically, if you had a fairly stock FC with a bad stock bypass valve. And you already had both of these sitting in front of you. Which would you put in, and why? Also, are there proven benefits for either?

 

the aftermarket for the sound. recirculate it to not run rich between shifts.

 

They're both aftermarket. I know you meant the atmos bov, though. Everywhere I read people say recirc is better, but everyone wants the sound.