Will a after maket forge intercooler be a direct replacement for my normal intercooler on my 1.9dci???

Yes IIRC DCi and 225 IC's are the same but there is little point in bothering. Diesels are much less sensitive to charge temps in terms of reliability or maintaining a power level than petrol engines. The denisty of the charge as a result of more efficent IC can yield greater output but really you need to see if the standard IC is causing you an issue in the first place. I suspect it's not.

Cheers
M

but surely if a better intercooler cools my engine down ud get better performance out of the car.