I have a 306 on my 37gal and I find it to be enough flow and filtration. However, I'm a fan of overfiltering and have a 2nd canister running so I have more than enough :icon_wink. The goose neck output does a a good job dispersing the water.
+1 on the adjustable flow. I have a 306 on my 29 gallon, and it works great. But I don't think the 406 would be to much on it.I used the original tubes, inlet and outlet at first. But I changed to regular clear vinyl tubing/ and this inlet/outlet later on.Stay with the 406. The flow is adjustable if needed.