Are you sure it is new? Looks like butterflys etc all have dirt and filter flange looks dinged up. I know pics can be deceiving. I may interested. Maybe a clearer shot of throttle bores would clear it up.
Never used on a running motor. But was used to mock up a Procharger setup, and has been in storage since. The brass will color from sitting. I can give it a bath in carb cleaner and see if it looks nicer.
Its a Dominator type throttle body, so yes, its a 4500 and not a 4150. I also have a brand new set of FAST injectors that were used in the same mock up. 65#. Have not listed them yet.