[SCHMIDTY]

That looks like the connector that plugs into the stock exhaust actuator. Wouldn't be used on your custom exhaust.

 

[SCHMIDTY]

Also maybe the plug for O2 sensors. Do those pipes have O2 sensors installed ?
The fuel delivery system doesn't contain sensors for fuel pressure.
Try removing the spark plugs and crank the starter over. The crankcase might be sumped, high oil tank on that model Harley.

 

[SCHMIDTY]

Put a pan under the bike prior to cranking with the plugs removed. Overflow if sumped !

 

[SCHMIDTY]

I will try that in the morning, is this something that can happen from the bike sitting unused for 10 months as it was working 100% fine prior to that.

Yes the oil leaks past the cam plate check valve over time and loads the crankcase up with excess oil. The excess oil causes the crankshaft flywheels to drag thru the oil. It's a dry sump oil system so the crankcase normally has very little oil in it. The tech term for it might be 'windage'.