I just looked under my car yesterday and the aluminized looked pretty good (2-3 years)but my car hasn't seen much weather. I also just recieved a new magnaflow muffler for my truck that said it was the satin stainless and it does appear to have a different finish than the one on my car. A magnet still sticks to it but it is probably just a lower grade stainless. Magnaflow used the same part numbers and changed all the almunized numbers to satin stainless. I think the only way you would endup with a aluminized is if it was sitting on a shelf. I got my muffler from
Performance Peddler They had very good service and free shipping. If you type in dtworld under the login it will give you a discount. I think you will like the price.