IMO

stage 1 = 270 chip, cone filter, exhaust.

stage 2 = 330 chip, 3 bar map senson, -31 actuator, filter, exhaust, rs500 type intercooler.

stage 3 = as stage 2 but with the addition of a T3/4 turbo

basicly the above stages are off the shelf parts that can (if you're confident) install as a diy job.