i did the search nothing that will help. The rattle is coming from the header section and not to be in denial sounds like its coming from the block. But its hard because of the exhaust. I have a VAFC and the rattles startes every time at 1600 rpms and 4400 rpms and thats it (dont seem to go away that much hot or cold). i dont have a CAT or the heat shield covering the header. If you do think it could be in the block (worst case) what could it be.

Thanks in advance

 

your worst case would probably a broken valve spring or you have a problem with a valve (you could swallow a valve) but that would be worst case. the problem is that a rattle is something that you have to hear to diagnose and we cant do that over a forum. good luck finding what it is.

 

May be any loose bolt around that area, they will vibrate at certain RPMs. Id suggest checking all the bolts in that area of the bay, check your header bolt connections as well, up top, as well as down at the mid pipe connection. Check to make sure your O2 Sensors are tightly fastened. If it comes down to it, take out your header and inspect it, make sure theres no foreign objects lodged in it. I highly doubt that would be the case, but you never know, ive been surprised once before.