This is Gary Stone’s wild twin-engine 2005 Citroën C2. It started when his previous C2 project was totaled in a garage fire. Instead of giving up he replaced the destroyed C2 with another one that he was planning on using a Honda engine in. Instead he decided to install a pair of 2.9 L ES9 J4 V6 engines from a Peugeot 406 coupe in the front and back. Each one produces 194 horsepower and 197 lb-ft of torque from the factory for a total of 388 horsepower and 394 lb-ft of torque. The front engine sits on a pair of custom mounts while the rear engine sits on a reversed Peugeot 406 subframe. Both engines run their factory five-speed transmissions with custom driveshafts. The rear axle has been welded to lock the differential. The engines are kept in sync with an ECU that allows for a bias of up to 500 rpm difference.
Source: PistonHeads (build thread)