All depends on what you want from the car - big power or daily driveability, etc

If you want to run big power id suggest spending more money on the PD manifold mate - have a look on archive posts on the RSOC and you'll see that although the miltek is much cheaper it comes at the expense of poor fitment (i.e grinding down bolts, leaving a turbo bolt off, etc) not good

Bear in mind going the gt28 route you should also budget for a boost controller, maybe a live map, etc, etc

Best bet would be to give Rob @ SCC a call as hes tuned a number of quality FRS (including mine) to high power on the GT28