stages mean nothing to anyone as one mans stage 3 could be the next mans stage 1.

when ordering a turbo or anything that can come in stages, the way to buy is ask for exactly what you want.

One of my rivals state stage 4 turbo £x amount of money when its not even the same as what I would call a stage 2.

dont be scammed ask for a larger compressor housing, 2wd cosowrth or 4x4 not machined out.
oversize bearings and shaft on any recon turbo
new back plate not recon
staggered oil seal
360 thrust kit some offer cheap and expensive versions of these.
modified core for the 360kit
larger .48 exhaust housing
cutback blades not required on low boost application
decast polished ex housing
balanced over 100,000rpm for decent use.

so as you can see if you dont ask you WONT get. I worked very closely with a leading turbo manufacturer for years building my own units and seeing behind the scenes so got a decent understanding how these company's work.

hope that helps