car is 2000 z28 a4.

at times my car seems to make a ticking noise, sounds like from head area.

the oil pressure usually is at 40-80. when it ticks it still has power, but seems like i have to hit the gas harder.

the oil level is fine, but when i changed my oil on the plug, was a small amount of grey stuck to it.

when I rev the engine and let go of the throttle, the rpms seem to drop quicker than normal.

I also have what appears to be an exhaust leak by the driverside exhaust manifold.

 

Fix the exhaust leak first.