i have two digital designs 3500 10" sub woofers (series C or D. dual 4). I need to find a Digital designs 3500 15" sub woofer for my new build. can anyone help me out. these two subs hit a 154.1 burp and a 152.4 streetbeat thirty second run at usaci finals last year. they are loud and i have had not one problem with them. Thanks
