What does this sound like to you? I get what sounds like a resonant buzz/rattle under WOT hard acceleration, right when RPM hits 5800-6000 just before the shift point. Coming from near the engine toward the passenger side. Take a listen here

https://youtu.be/rrgM9O7OIOY

 

Kind of hard to tell in the video. Usually rattles that come from the engine compartment are heat shields that are hitting against something. I would check the one around he exhaust. Maybe see if you can replicate the sound with it in park and the hood open so you can peak around.

 

Wouldn't want to do that in a no-load situation. I think the engine self-protectively rev-limits around 3000 if you are in neutral or park. It won't rev that high unless you are in gear under load. But, I think you may be right, does sound like vibration of an exhaust shield. I need someone to look at it on a lift, tap on it and see if it's loose

 

I think I have this same issue, I rarely ever drive my car hard so I haven't gotten around to figuring it out. I have a feeling in my case its the big plastic covering under the windshield which rattles when the motor is really buzzing. After removing it multiple times between the lost-motion spring recall, swift spring install, and windshield replacement, I'm pretty sure only 2 clips were left intact there...... not sure this is it, but post if you figure it out...

 

Mine's been off maybe twice for the LM spring recall 3-4 yes ago, and just recently for valve adj service @ 71k. But this sound is def metallic, and from down under the car, near the firewall, passenger side

 

I just got my 2013 Fit Sport with NAV, and I have this EXACT issue.
Did anyone figure out what this is?
Timing chain tensioner? Heat shield? Plastic windscreen shroud?

 

The crosspiece which runs just under/near the catalytic converter got bent/pushed upward somehow and was making contact with the exhaust, causing a buzzing/rattling noise at certain higher engine RPMs. Had it inspected, simple fix, just tugged on it and bent back down away from exhaust. Not much of a bend, just an inch or so. No more issues

 

I had noise on my '11 Sport and then it stopped. I went back and picked up the catalytic converter heat shield that finally fell off.

 

Mine does this too . I'll check the heat shields . Thanks.

 

Lol.. Reading this reply reminds me of taking the rotten heat shield off of my old del sol. Never bothered replacing it, although i was careful not to park on dry grass .... Luckily dry grass and low slung convertibles don't frequently overlap in the course of things..