An audacious plan that just sort of worked out. The factory single piston floating calipers, no matter how much I lubed the sliding wedges always dragged. As a joke the idea came up to consider sport bike brakes for my tiny car and late that night I won an ebay auction for a pair of front calipers, lines and pads off a 2008 GSXR 750 for the 9.99 opening bid.
When they got here I first took them apart and measured the pistons. each side has one 30 and one 34mm piston. Total area of 1615sq/mm. The fiat caliper has a single 45mm piston with a total area of 1590sq/mm.....Woah!!! that is so close as to be scary. Brake biasing will be unchanged.
The only problem is that they wouldnt fit over the thicker rotors but that was easy
Some aluminum spacers cut out with a recessed hole for the internal fluid seal
An extra seal, some powdercoat and done
An abarth decal for bit of detail
Fabbed up a pair of caliper carriers
At this point I was all of about $15 into the pair but I had to have custom brake lines made at $32 each 
ouch! But they are DOT legal braided stainless with the proper banjo fittings for the calipers and the original fiat ends to fit into the chassis mounting clips
This morning I had the chance to put it all together
Started with this 11lb mess
and installed 3.69lbs of sportbikey goodness.
Driving impressions? The reduction in unsprung weight is awesome. The car actually feels faster. Less banging and crashing on bumps as well. After bedding the pads in the first real stop almost made me bite the steering wheel. Modulation is better, before they were kinda like a 3 position switch. off/kinda on/locked up. Now they work like.....gasp...modern brakes.
So there it is my $79 brake upgrade. Gixxer brakes on a car.
And the rears are in the works. Thinking about doing the exact same thing (the factory braking is 50/50 bias) and using a pair of cheap go-kart mechanical calipers as the ebrake
