I finally couldn't take the squealing noise anymore so I took it in for repair. The Suzuki rep recomended the main bearing be pulled which required my block to be pulled out. Long story short it still makes the same sound, maybe louder. While it was in for repairs the mechanics destroyed the paint job on the lower unit and the cowling, and ruined one of my hatch covers - but that's another story.

Plus... my other 175 is burning about a quart of oil every 25 hours. Maybe this is normal, but the other engine (the loud one) burns zero oil.

I've called Suzuki headquarters to beg for some advice on the sound, but they just tell me to take it to a certified mechanic.