215/45/17 should not be rubbing even with full load. i got the same car as you and with the same size tires, and no rubbing. if you're rubbing now, and you want to drop your car more, you'd probably be rubbing alot more def.
i got myself a AEM cold air intake for my car. probably one the best things I ever spent money on for my car!! I'd def. recommend you get an AEM cold air intake. Since I'm from jersey, I went ahead and purchase a bypass valve for the intake as well. many people say you don't need it but, all the rain/snow we get here, I thought it was money well spent (peace of mind
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PS- FYI: there's alot of info on this board, you might just want to do a search and it'll help you out, you don't have to wait for an answer.