Golf IV R32 :: In Cabin Noise When Accelerating / Deep Metallic Grind Noise But Car Drives Fine?

I've been working on my car for a few weeks now and I've been doing my best to figure out. The source of this sort of 'metallic grinding' that I'm hearing within the cabin. I cant seem to pinpoint where it's coming from within the engine bay with the hood open (maybe due to the magnaflow exhaust diffusing the sound from the outside of my car). I can easily hear noise when I'm inside however with indications its coming from the lower central area of the engine bay. I drive an '04 Volkwagen GTI 1.8T

In the days I've been working on it I've replaced the:

1. Timing Belt (and tensioner pulley/tensioner dampener)
2. Water Pump
3. Serpentine Belt
4. Thermostat (and housing)
5. Clutch disk and flywheel (from a SMF to a LUK DMF clutch)
6. CV Axles (both drivers and passengers)
7. Clutch Cylinder Slave
8. Wheel Bearings (front left and right)
9. Rotors (Front Left and Right)

Diagnosis**

The car starts without any problems just as it use to prior to the replacements done. BUT it's once I get the car moving where I begin accelerating I start to hear a dull grinding noise/rumble that becomes more and more apparent the faster I go. It seems the sound is directly correspondent to wheel movement upon accelerating. Nevertheless I could be wrong.

I had a friend tag along to diagnose the sound and to him it sounded similar to the "tunneling of air not being properly sealed" but to me it sounds like a metallic grind. My friend also mentioned that he felt it was louder towards the passenger side in contrast to the drivers. As mentioned before the sound is reproduced anytime wheel movement occurs. I've checked torque spec for every replacement job done to the car so there are no loose bolts/nuts/brackets. (but there are exceptions, which I will get to).

Knowing that I've replaced both of the wheel bearings (and hub assembly) I can only assume the sources isn't from there. But I do admit a few mistakes while I had the car on jacks.

1. During the timing belt replacement I thought I would need to remove the exhaust (because I felt it would interfere with the lowering of the engine) so I, (without success), tried to remove the connection between the "bend of the exhaust" to the manifold which were 4 'turbo studs'. I had the worst time with the removal of studs but I was able to impact one them off, and as I tried another the strength of the impact broke one them half way through (meaning that I was able to unthread it a few threads but it snapped in the process, so I would need to somehow drill it out in order to replace it). This is where I gave up and did my best to install the one I had removed. Which I could only get threaded half of the way in.

-All in all I have 1 broken stud that still making a connection, and 1 protruding stud out of the 4 that connects the exhaust to the manifold.

Question: Can this be the cause of the sound? Without the full connection of 4 studs bolting exhaust to the manifold? Can this be the sound That my friend was referring to as the "tunneling air not being properly sealed"?

2. The second "mistake" isn't necessarily a mistake but a fault I found later that has to do with the Passenger CV Axle. I read a few forums here and read that it could be a problem with the axles, so I put the front end on jacks once again and found that there was a bit of movement of play on the axle shaft itself. In detail, the 2 connection points for the axle both at the Output differential flange and Hub assembly are secure and torqued to spec without any loose bolts.

BUT the rod itself seems to shift about a 1/2" between these two connecting points.

Question: Could THIS be the problem? With this type of 1/2" shift in the rod is it possible it can recreate the dull metallic grinding I'm hearing so much?