I see nobody has mentioned misalignment of any valve bumpers. When I got my Eb the first thing I noticed was it sounded stuffy in the upper register, Bb, B, C, C#, D, Eb, E and F just wasn't speaking. I opened the tuning slide and shined a light to the 4th valve and noticed it was closing too far. After redoing the bumpers on that valve the upper notes spoke more freely. I eventually repadded and aligned all the valves and its like blowing through an open tube from bottom to top. I also found that reversing some of the valve slides can affect intonation. By that I mean just putting the slide in left side of slide to right side of receiver. Just make certain that diameters are equal. Also, check the water key. A weak spring or slightly angled out of place cork can create intonation problems.
If you have the opportunity, play with a strobotuner using different intervals and see if blowing pressure solves intonation issues.
Have fun.