The b has the Hitachi ECU which is extremely difficult to split and chips within it cannot be written to. Even if you put C&B into her, you wont get the full benefit without altering the map.
I gave up trying to find a way of upping my power via the ECU. You may be able to piggyback something, but I dont like that route myself.
The engine was originally from the '94 Fiat Coupe and barchetta, I may be wrong on this but I dont think the 1.8 Coupe came to the UK. Which came first is debatable, I think the Coupe did! It was then used to good affect in the Punto HGT from '99 onwards.
I think the best and cheapest method is to install controllable NOS - i.e. not the big bang, bottle in a minute installation, one that is controlled by yourself so you can add as little or much as you want, and it will work in control with the car. This is theory though, not something I have tried as I have kept the b standard except the wheels, the exhaust, the hood, the induction side, the brak.........
There is a guy we use called Peter Betts who runs Thor Racing in Warwickshire, who is one of the best guys I have met in the industry.
he installs these and can also scratch build you an ECU too, if you really want to go that route..
Hope that helps a bit