ARC box or Apex'i filter w/ pipe?
 

Exactly as the title describes, ARC box or the Apex'i filter with a suction pipe i.e. cusco pipe... which would provide better gains with or without S-AFC?

Also, will the ARC box showoff the sound of the turbo and DV as loudly as an open element filter would?

it all depends on your mods. if you still run the stock turbo w/ maf, stick w/ stock. if you've upgraded to a map sensor and bigger turbo, get one that can block some heat from the filter. as far as the sound goes, any time you go w/ an open air filter the sound of the turbo and the bypass valve increase a but load. i ran the hks suction for a while and it was LOUD. however, once i put my stocker back on i gained an ass load of torque back. it's been hashed over and over here, but you better have engine management, and the know-how to tune around the filter that's pushing way too much air throught the maf.

So a tuned S-AFC wouldn't help, I'd need a standalone, or a re-tune of the ECU?

yes the ARC box does give you bov sound

an safc would help, but standalone or piggyback would be the best.

You need to check out the new Apexi intake box for the EVO. It looks great and it isn't too much $. Here is the link.
http://www.apexi-usa.com/news.asp?ID=64
They have it pictured on a WRX and an EVO.