- BEST OF C2 S1600 & MAXI - PURE SOUND - CHECKPOINTRALLYE - 

Sequential gear box and straight pipe I would imagine also remapping rev limit etc

ITB's

They rev very high and as someone else said, they use straight pipes.

İntake throttle body, straight pipe and very big cam maybe 320-330 degree nothing else only these three things..

Blueprint engine, which means: complete rebuild with stronger and higher compression pistons stronger and lighter conrods lightened forged crankshaft lightened flywheel work to the head to make it flow better, install bigger intake and exhaust valves and high rpm valve springs race spec s1600 intake and exhaust camshafts s1600 Citroen sport race spec intake manifold ( single throttle body ) OR Individual intake manifold Race exhaust, basically a straight pipe Then a sequential race gearbox like a Hewland This car should have around 225 hp and can rev to 9k rpm