Two things to remember about aluminum frames:

1. They are extremely noisy when compared to steel.

2. They conduct sound extremely efficiently.

That means that some noise is inevitable. You can minimize this by greasing bolts and contact points [seatpost, saddle rails, stem/handlebar clamp, etc.] It also means that the noise can be comong from almost anywhere on the bike, but is being transmitted at equal volume to every other squeal and click The noise could be just as easily a loose chainring bolt transmitted through the BB and the frame, hup the downtube to your handlebars, or it could be the seatpost clamp moving against the saddle rails, or it could be a crack in the frame. lopcating the source of a noise in an aluminum frame is a lesson in frustration.