Davey,
Welcome to Impala SS Forum.
There are a number of publications and sources, including GM High Tech Performance magazine, as well StreetTrends, Year One and other big companies that carry multibple lines of products for the Impala SS.
You can find some of this information as well by joining ISSCA, which gets you a year (6 issues) of Impala SScene magazine, which has a number of Impala-friendly vendor/advertisers in every issue.
Just go up to the top left corner of any page of Impala SS Forum to find out more about ISSCA.
You should also check the Vendor section of Forum for products for the B-body, too.