I’ve only been to The European Sausage Kitchen once, but I can say that their kielbasa comes very close to what I buy when I’m in Brooklyn, NY. I belong to many of the Mazatlan Facebook forums and the Yahoo group, and have been following these guys for a while now. I’d planned on going during past visits to Mazatlan, but never quite made it. One reason is that the description of their location didn’t click in my head.
The European Sausage Kitchen is right up the hill from el Mercado Pino Suarez. If you get on the Sabalo Centro bus going towards the Gold Zone, it’ll go right past them. Save yourself the 10 pesos and walk the 3 or so blocks! Up the hill, and then a couple of storefronts as you’re going back down the other side and you’re there!
The place is extra clean, and they have a little steam table setup with samples! Good prices. Excellent sausage. Central location. You can’t really beat it!
For more information, and notices of special items that are available, give their Facebook page a look: European Sausage Kitchen FB Page

Map: European Sausage Kitchen (was Papeleria Sara)