XU10J4R RFV tuning project (Xantia)

[amirxnt 0]

Hi everyone
sorry if my English is poor.

I have 2009 (yes it's 2009!) Citroen Xantia 2.0 16v with XV10J4R RFV engine. I kept it for about 11 years standard because I use it as a daily car.
But now I want to increase the power like a project car.
For legal reasons in my country, I can't change the engine volume and the number of cylinders! So the block must be XU10 and can't change it. (I wanted to use ES9 block)
Because I still want to use it daily, I want about 250-260bhp and no more. Here (Tehran-Iran) is about 1.4 km above sea level and its pressure is 850 kPa.
What do you suggest for this project? use turbo or not? use another version of XU10 (like XU10J4RS, XU10J2TE, XU10J4TE, etc.) or make it (XU10J4R) custom?

[dcc 855]

Bolt a super charger to it