Strange sound from Engine/Exhaust

[malkduds]

Hey everyone back again to ask about a weird sound that popped up one day..Had a read through several threads and couldn't find the exact issue/sound

The sound is a bit like a metal pipe vibrating, a sort of high pitch whine.. I uploaded a video and enhanced the audio a little to make it more easy to hear, will need earphones though to hear it right (ignore the reflected video - I'm clearly a youtube noob) -

The sound starts at the very beginning but can also be heard at 0:02/0:07/0:10/0:12 - pretty much anytime the tach moves past ~3400rpm

For context:

• the car is completely stock, MT 2017 86gt (manufactured after the new TOB was put in).
• I'm pretty rough on my car and redline pretty much everytime I drive it, which is more or less daily (but always check the oil temps and have never gone beyond 112C as the absolute max temp - usually 109C after some abuse)
• I rev match and heel toe so its not like I abuse the clutch all that much
• oil changed happen ~ every 6 months which is ~7000km for me
• I run a 5w30 synthetic oil because here in australia oil temps easily reach 100C granny shifting and pretty much sit at 110C when redlining a few times, before traffic means I have to drive normally again...
• I cracked my intake at one point but fixed it using a soldering iron and some copper wire to reinforce, didn't hear this noise when the air intake was cracked (was only cracked on the corner of the box opposite side to the engine - cold air side?) also didn't hear it after I patched the air intake just started happening randomly one day

Characteristics of the issue:

• The sound appears to happen when ever I pass through 3400rpm (revving in neutral, all gears 1-6)
• I feel like maybe throttle response is less - but that could be me
• And that power might be less than before - also could be me getting used to the power delivery
• I definitely can't hear any of the pops and crackles that happen when you ease off the throttle and the engine is up to operating temps - used to hear that a bit here cause of ambient temps and the exhaust getting hot
• while the engine is warming up - oil/coolant not yet at operating temps I can't hear it due to the roughness of the engine sound, but even if I listen for it I can't seem to hear it while warm up is happening
• from listening with a screwdriver to my ear the sound isn't in the engine/air con unit, I feel like I hear it below in the header
• tried plugging the sound tube through the firewall, it stopped it sounding so loud but if I listen I can still hear it beyond the firewall

Is it possible given how hard I push the car pretty much all the time, that the exhaust is busted or maybe the cat is starting to break down in the header? Or maybe something is rubbing against the engine as is vibrates seeing as peak torque hits around 3500rpm before it drops off again for the infamous dip

What would be your next steps to investigate this sound? Or is it yet another sound coming out of the car as it ages?

Keen to hear your thoughts

Malkduds

[Tcoat]

Heat shield. Although I couldn't hear anything in the video.