Ticking at idle

[2015 High Miler]

2015 Sierra 5.3, 200,000+ miles 

 

It’s had this tick, off and on for a while. Now with headers and a tune, it’s a little more common.  At at idle, it’s almost constant but rev it a few hundred rpm, it stops. 
Listen here

 

It’s done this just about since I got the truck with 36,000 miles. I really notice it in drive thru’s but it does seem to be more noticeable with the headers. 
 

Any ideas on what it is? Assuming it’s a lifter but it’s been doing for ever so I’m not really sure as I’d assume a lifter ticking like that would fail by now. 

[CamGTP]

My guess would be the high pressure fuel pump because that is driven off the camshaft at that rear of the engine. They can be noisy at idle.

[ford5of5]

I'm experiencing the same tick at 40k miles on my 2015 Sierra with 5.3. To me, it sounds like a lifter tick. I'm basing that on my experience with cars from the 60's, 70's and 80's, so it's entirely possible that CamGTP is correct . On my truck, the tick is on the passenger side, about mid engine. It only started recently and I haven't had time to check it further. I have noticed a drop in mpg based on the trucks DIC; I drive like a granny, mostly suburbs and highway, and can keep it close to 19 mpg. 2 oil changes ago, I saw a drop in oil pressure at idle from 40 to 30. I believe I may need to swap out the pickup tube O-ring. If restoring the the oil pressure back to 40 doesn't make the noise go away then I will start tearing into the engine. I'm not getting any CEL's, noticeable misfires or loss of power; haven't tried checking for codes yet.