By right side of engine, I'm assuming you mean the left side of engine behind dipstick? I'm pretty sure right and left are always from car's point of view, not yours...which is why in US, I always tell guys driver's or passenger side...just to be safe.
Anyway, rectangular black box maybe 1" thick, 3" high and about 5" long?
Isolate sound with a hose in ear or stethoscope. If it's hissing from there, pretty easy to get to and get it off. There is a gasket that can be replaced...and DISA's go bad pretty often from what I hear.
Many other places for air leaks, so before you go replacing a million parts, isolate well.
As desperate as this sounds, in comedy, 'likes' and 'views,' 'friends,' and 'retweets' really help. If I've ever helped you, please help me by friending, liking, viewing, and retweeting. It makes others think I have a following...it'll take you a minute or less. If you could, I'd really appreciate it!
A recent set--NSFW audio: https://youtu.be/_dcxcZfD6dg
Mangofy your E46!