Hey Mike, missed this message. In my MG-Is, the crossover cap is 12 mfd, but the inductor is unlabeled. I replaced the caps with equal value Solens polypropylene, but didn't hear any audible difference between them and the stock electrolytics. Something that was quite surprising considering my positive experience with this action in other speakers. I suspect that the inductor might be worth upgrading as well to a good foil type, but the value is the question.The one schematic circulating the internet for the MG-I crossover is wrong wrt the capacitor stating that it's 13 mfd. Thus the figure given for inductor at 0.33mH is suspect as well. My very rough, quick'n'dirty calculations indicated a value of 0.30mH. Well, that's pretty close considering, so you might not hear a difference betwixt the twain provided the same is done with both.
Something to keep in mind is that no matter what you do to the Maggies, they'll always be a bit veiled. They just don't reproduce low level detail all that well (especially at low volumes) and won't have the same transparency as you've become accustomed to with the Altecs. Of course, the first time some fine female vocals give you goosebumps, you won't care.
- JP