How big of Intercooler piping?

[Forced Fed]

The engine is a 750cc Weber Parallel Twin Four-Stroke and uses natural aspiration standard, and it’s rated at 80 hp. However, get the turbo version that adds a small K03 turbo that spins up to 200,000 rpm and watch it crank up to 135 hp. Get the Polaris 2007 reflash and you are at 150 hp.

Now my goal is to make 170-210 hp out of this engine, I've heard they can make 250+ hp.

Here are the mods I plan on using:

15.5" x 7.5" x 4" FMIC
Ported Garrett GT2854R Turbo
Custum Tubular Header
3.5" Aluminium Intake with AMSOIL Air Filter
Polished Ebay Oil Catch Can
Some sort of exhaust once everything else is in place

Now I guess how big of Intercooler piping should I go with, I was thinking 2"?