Nothing massive but thinking is like to end up at 200-250 mark in the end by the time i do everything??
There is a huge difference in 200 and 250bhp. Depending on engine code, 200bhp is achievable with nothing more than a remap. 250bhp requires a whole lot more.....silicone tip/boost pipes, turbo back exhaust, FMIC, injectors, maf, fuel pump, actuator, probably turbo then custom map.
as its hes first turbo car he wouldnt know that.
and its not the case you "can not" run a open or vent to atmosphere dump valve, its the case that the charge thats dumped will be lost to air, and as the ecu has accounted for the air its just dumped, causing it to run rich, so its not recommended.
ko3s and remap will yield 250. and the ko3s is straight swap. or for the extra effort a ko4 gives better drivablility. and pulls stonger.