Hey everyone, I haven't been an S2000 owner for long and I don't know a lot about mechanics (a problem I am trying to fix) but in any case I have a question about a strange noise. When the car is in gear and I take my foot off the gas it makes a slightly louder/deeper sound then when I'm on the gas. The lower the gear the more noticeable it is. Honestly I didn't really pick up on it until now cause with the top down its pretty hard to hear but with the top up the sound is clearer. I can't tell exactly where the sound is coming from. Does anybody have any suggestions?

Thanks!