Duct Booster vs. Inline vs Muffin Fan vs OTHER...what is best for my small space?

My tent is 4ftL x 2ftD x 5ft H....40 ft2

I can't pick for the life of me.

I need it to accommodate (through design or duct tape LOL) a carbon filter.

Help me please!

I had a 400w in a space not quite as long and i had to spend the money and get a good quality 4" centrifugal to run through a cool tube and another 4" pulling through a carbon filter. I was able to turn them down abit making it alot quieter. T5's and you should get away with just one fan on a filter. I'd say get something 100 cfm min. but 150 cfm or so would be better then you can turn it down if you like.

^yeah, this

I've bought a 4" duct fan, a 6" duct Fan and a 6" Hydrofarm Centrifugal....

...1st off, those 4" fans can't be stepped down with any rheostat I know of.... well then again maybe this one
Suncourt Variable Speed Fan Controller SCP

...the 6" inline can be controlled with those cheapo router type speed controllers for like $20....but they don't have the pull
...anyway, If I had to do it all over again I'd just bite the bullet for a 4" centrifugal.....

Inline, and like mentioned above a speed controller helps a ton