How big of Intercooler piping?

[Forced Fed]

Stock boost for a winter, then eventually switch to E85 (even though winter blend sucks) for more boost and to have extra exhaust gasses to spool the "monster " turbo.

I've been trying to figure out how much boost FS-Ts run stock, I saw somewhere a company was selling a stage 1 reflash that was 18.5 psi but that seems a little high?

So intercooler is needed, plus they tend to overheat easily as is because of the turbo, that's why they had the reflash in 07 to help correct the over heating problem. Funny enough the reflash gives an extra 15 hp.