While it’s certainly possible to build much larger small-blocks these days, the good ol’ 383 keeps chugging along. The same balance of performance and value that made it popular decades ago still applies today, and Competition Products’ 383 proves the point. For a little over $4,000, it kicks out 410 hp and 450 lb-ft. The company starts with a four-bolt block, punches it -inch over, then fits it with a cast Scat crank, steel rods, and :1 hypereutectic pistons. The short-block breathes through aluminum cylinder heads, a dual-plane intake, and a dyno-tuned carb, all from Edelbrock. All you have to add is a water pump, and this puppy’s ready to fire up.
Due to your vehicle being an early type of particle filter it will require changing at 60000 miles as well as filling the additive tank with ( dpx42 ) and resetting on the computer .but what I'm sure you want to know is the way to recondition the unit for next to nothing , remove the particle filter , ( careful not to damage pre/post pressure pipes ) and soak unit in brick acid ( builders merchant ) then with full face mast steam clean until water flows through unit clean . Refit . Filling is easy but you will have to buy the kit from main dealer and get a Peugeot/citroen dealer/specialist to reset fluid level in the particle filter Ecu but as previous posts have said it will keep loosing power until the particle filter blocks and won't go over 20mph . It sound a lot of messing but a dealer will charge £600 plus so it's worth doing the regen instead of replacing . Best of luck ( I've worked for Peugeot for 20 years do I KNOW this works )