hey...i hear a rattling, but only at 2500 rpms...sounds like metal and sounds like it's coming from the lower portion of the engine bay...like by the exhaust mani...was wondering if this is heat shield rattle and what i can do about it...also...started after i got a resonator installed...any other causes?

 

It might be the cat. I had the same problem a while back with my stock cat at around 2700 rpms.

 

Its a manufactuing defect, if it happens around 1800 RPMS and is louder when you rev the engine up, then let it fall off...Yeah its the exast, i belivce the downpipe, honda knows about it and can fix it for some $$$...

 

I had the same problem.
It turned out to be a shattered down pipe. If you take a rubber mallet, and give your pipe a stiff knock, you should be able to tell if thats your problem. If it's damaged, you'll hear loose pieces of metal inside. Also, while you're there,.. check the gasket between your cat and down pipe.
Some guys claim the rattle is from the heatshield, but that wasnt the case for me.

 

thx...i think i'ma just take it back to the guys that installed the resonator...they better not have busted something up