Question, don't know what to type to search either, but I have a stock Vortexh pully and kit on an AP1, I thought I heard somewhere if you have an Aftercooler you can get a smaller pully to compensate for the pressure loss of the Aftercooler. Is this true and since I have the stock black box and FMU that comes in the kit, how would I tell?

 

Bump 'n grind lol.

I'm not sure if you've been answered in the past 10 years but if you haven't: the beauty of the aftercooler is that there is no boost loss as opposed to running an FMIC. I run the stock aftercooler my Vortech V2 came with on my AP1 and it's a short path to the throttle body. I see 10 psi (6.5" crank pulley + 4" blower pulley at altitude) if the belt doesn't slip at 9k rpm. If I swapped that out for an FMIC I'd definitely lose around 2 psi.

You can only tell how much boost you're making by either running a boost gauge like an AEM boost gauge or checking the MAP feedback at WOT in your tuning software (AEM Series 2, Infinity, Haltech, Link G4, etc).