FYR, the original Amplifier was (obviously) made by AMP Research In Laguna Beach but your Amplifier 2 (& the rear end of the Litespeed above) were made (in China?) by the Canadian Company Kinesis
The first batch of Amplifier IIs were made in the States. Frank Wadelton welded up a bunch of the rear ends for Mongoose (who then ignored his invoices and stiffed him). You can see the differences between the Amplifier II and the Amplifier2 in the pic nigelb posted in his thread on his Amplifier II.
I've made a number of changes to mine this year. Yellow Z1, Hope Ti-Glide+C2 brake on the front, LX drivetrain+shifters, Paul Crosstop on the rear (still need to swap out the red for yellow Kool Stop pads), Rhino Lites, and Tioga Psycho IIs. Happy with it now (aside from the red pads).