there is a huge amount of variables to consider when ur thinking of boosting that much, pushing the engine and car beyond it's intended spec closer towards failure.
any performance modding project is about the balance of budget, timescale, resource, effort, reliability, safety, legislation/MOT.
but I'll use mine as an example. originally I got the turbo setup from a previous owner so most of the hard work was done but here's a list of everything that needed upgrading/change.
I run 10psi, 160bhp, 160ftlb, standard 1.3 internals (up to now), using it daily with occasional track days.
FUEL
98ron super unleaded
walbro 255lph pump (previous GTS-T pump couldn't keep up with 160bhp near the redline on trackdays)
http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-36#post-482610
modded sr20de fuel rail & sr20 regulator (came with the turbo kit)
then upgraded to 370cc injectors from a 200sx
http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-20#post-448174
EXHAUST
custom manifold (came with turbo kit)
http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-45#post-503515
TURBO
T2/T25 hybrid
custom oil feed (from the oil gallery plug near exhaust manifold) & custom oil drain back to sump
http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-23#post-453731
had to eventually rebuild the worn smoking turbo
http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-39#post-486823
DRIVE TRAIN
200mm helix organic clutch on stock flywheel (to guarantee it'll handle the force & heat of 160ftlb on track days)
http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-42#post-501040
Gripper LSD (to maintain traction with 160ftlb but that much torque was shattering the preload ring repeatedly for some reason but its under lifetime warranty)
http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-50#post-509271
BRAKES
GTIR ad22v calipers (for high speed braking on track)
http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-3#post-395713
black diamond grooved discs
http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-53#post-514095
black diamond predator FT pads
http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-53#post-515275
15" Rota Grid forged alloys with Toyo T1R (massive heavy brakes needed at least 15" wheels to fit. sticky toyos was a major increase in grip)
http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-3#post-395713
COOLING
thicker 26mm Nissen radiator for an automatic k11
http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-44#post-502988
ELECTRONICS
Nistune daughter board (after fitting the turbo, was remapped on a dyno by Ed at fusion motorsports)
http://micra.org.uk/threads/pollymobiles-rebuild.35251/#post-381122
colder BKR6E NGK plugs
Innovate LC-1 / XD16 wideband kit
http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-15#post-437898
DIY electronic WOT boost controller
http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-45#post-503265
INTAKE
pod filter
http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-21#post-449929
custom inlet/intercooler pipes
http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-49#post-508426
Saab 9000 recirc BOV
http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-11#post-421475
GTIR MAF
http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-47#post-505220
disconnected TB coolant lines (keep TB cool, will need to remove the fast idle waxstat mechanism)
http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-44#post-502488
DIY teflon inlet manifold spacer (keeps manifold cold)
http://micra.org.uk/threads/pollymobiles-rebuild.35251/page-50#post-510149
INSURANCE
increased premium, and with at least 12 mods, very few companies will insure it