Ok some tactics I don't see enemy Howie's use enough:

1. I too often see Howie's not push a lane very fast because they're unwilling to use the slow grenades. I like to walk out to the side of the wave as it's hitting my wave, Right Click and make the spread hit the entire wave, and then simultaneously Q the wave. The result is an instant wave that's either 1 hit or half health away from clearing. With CDR you can get your next Q out before the wave dies. And with armavore, you get a tone of mana back for that combo.
2. The Getaway combo: You get ganked. Instant Ult, and ult the path you need to go towards to get away (behind you most likely if you've been pushing). Then, as soon as you hit the ground, E and cast again so it pushing you away. Then spin around and through your right click down. If you don't have your cooldowns ready, hang up in your ult before casting for a bit to regain them. This will boost you 2x essentially away from the scary guys ganking you.
3. Ult the tower you're sieging with your team, they'll have free reign then.