At this moment im stuck triying to figure out which turbo will fit my aplication, but before hand im relatively new in the turbo world, just triying to avoid carpet bombing from people with more experience. Now what im working on its been done, im talking about a stoker turbo setup, yes theres a lot of info out and belive me im been doing some research in the small time i have left and its takes a lot of green guys cuz Im building this thing from the ground up. My issue now is trying to figure out a good turbine for this setup (t3/t4 combo, t3 or t4). At this point i just see numbers and equations and stumble in a quite few of them including calculators for boost, cfm and so on so on, the more i look the more complicated they get. until now i had play with garrett and turbonetic nunbers they (look the same) some others more simpler like Joseph obernberger at lovehorsepower.com and some places looking for compressor maps and my numbers differ from each of them. one of my main problems is getting pressure ratio some people use simple calculation as 141.7+psi/141.7 (aparently omiting factors like altitude, elevation and psi loss) others use TTc=P2c/P1c. To make the long story short if somebody with more expirience can shed some light of how to get the apropiate calculations ill be depply appreciated. Just need formulas not just use this turbo, this brand and so on, thanks