I was just wondering if anyone ever had a rattle coming from the engine bay at anything over half throttle?? I know this is a hard thing to respond to, but I just need some ideas. I just tightened my headers not a month ago, so I don't think that is it. It sounds metallic and I don't hear it when driving slowly or when it is idling. Thanks for any ideas...

 

Exhaust hitting the floorboard, or hitting something else?

 

So many things could rattle. Just get under there and start moving things around. See if you can re-create it by hand.

 

Viprklr has good advice. i had a rattle up front only when I went
over a speed bump (slow speed 'jingle-jingle) it drove me crazy.
finally started pushing down on the fender to make the front end
'bounce' like my dad (r.i.p.) would do to check a shock absorber.

I pushed down on the fender and released, heard the metallic
'jingle' and finally found it was the metal washers that were loose
around a bad plastic sway bar bushing.

different problem, I know, but the technique can work.