I've had a vacuum leak (along with a corresponding CEL for Small Leak & one for Large Leak)

I've gone over every hose under the hood, but with the radio off going down the highway and the rear sliding window open, I can here a whistle that changes pitch when I use the brakes, it's constant but get's louder when using the brakes.

Today I took the whole charcoal canister down and ordered a new Canister Vent Purge Solenoid from Amazon (free next day delivery for 36 dollars and parts stores didn't have them in stock and wanted 74, so that was a no brainer)..

I'm replacing the deteriorated lines back there with Fuel/Evap line, is there anything else back there that I need to look for?

The leak isn't enough to cause a rough idle, but it does affect the brake performance due to the booster having vacuum robbed from it.