Never heard of this plane before.
Did it play a significant part in the war? 
Here's from my G.55 Thread from a few months ago:
The Fiat G.55 Centauro (Italian: "Centaur") was a single-engine single-seat World War II fighter aircraft used by the Regia Aeronautica and the A.N.R. (Aeronautica Nazionale Repubblicana) in 1943-1945. It was designed and built in Turin by Fiat. The Fiat G.55 was,[2] probably the best type produced in Italy during World War II, but it did not enter production until 1943.[3] During its short operational service, mostly under the Repubblica Sociale Italiana insignia, after the 8 September 1943, this powerful, robust and fast aircraft proved itself to be an excellent interceptor at high altitude.[4] In 1944, over Northern Italy, the Centauro clashed with British Supermarine Spitfire, P-51 Mustang, P-47 Thunderbolt and P-38 Lightning. Italian fighter pilots liked their Centauro but by the time the war ended, only less than 300 had been built.[2]
General characteristics
Crew: 1
Length: 9.37 m (30 ft 9 in)
Wingspan: 11.85 m (38 ft 10 in)
Height: 3.13 m (without the antenna mast) (10 ft 3¼ in)
Wing area: 21.11 m² (227.23 ft²)
Empty weight: 2,630 kg (5,798 lb)
Loaded weight: 3,520 kg (7,760 lb)
Max takeoff weight: 3,718 kg (8,197 lb)
Powerplant: 1× Fiat R.A 1050 Tifone (license-built Daimler-Benz DB 605A-1) liquid-cooled inverted V-12, 1,085 kW (1,475 hp)
Performance
Maximum speed: 623 km/h (337 kn, 387 mph (417mph with WEP)) at 7,000 m (22,970 ft)
Range: 1,200 km, or 1,650 km with two 100 l (26 US Gal) drop tanks under wings (545 nmi, 627 mi (or 891 nmi, 1,025 mi with drop tanks ))
Service ceiling: 12,750 m (41,830 ft)
Rate of climb: 5 min 50 sec at 6,000 m (Dimensione Cielo, Caccia Assalto 3 Edizioni Bizzarri, Roma 1972, pag. 15) ()
Wing loading: 154.0 kg/m² (34.15 lb/ft²)
Power/mass: 0.308 kW/kg (0.190 hp/lb)
Climb to 7,000 m (22,970 ft): 8.57 min
Armament
G.55 Serie 0:
1 × 20 mm Mauser MG 151/20 cannon, engine-mounted (250 rounds)
4 × 12.7 mm (.5 in) Breda-SAFAT machine guns, two in the upper engine cowling, two in the lower cowling/wing roots (300 rpg)
G.55 Serie I:
3 × 20 mm MG 151/20s, one engine-mounted (250 rounds) and two wing-mounted (200 rpg)
2 × 12.7 mm Breda-SAFAT machine guns in the upper engine cowling (300 rpg)
Provision for 2 × 160 kg (353 lb) bombs on underwing racks
Yes it served in at least 3 italian squadrons that flew C.205s, g.55s and 109s
