You'll be able to achieve 165/170 max before having to change the turbo. People have had this car running at 230BHP with a TD04 conversion, but with uprated parts.
I myself haven't remapped but know people who have, some people have Multiair issues some don't. The TD04 conversion would require a lot of up rated parts and probably would shorten the life span of the car.
I could only get 170bhp from evo sporting with 2.5in turbo back with sports cat along with forge intercooler and induction system. I now have td04l fitted and it's running 220bhp with 20psi boost. I spent about 4k up to this point. My advice would b to save up 4 a faster car!