water/meth

Hey I am doing a rebuild on a 2018 Subaru wrx, with 40,000 miles. While removing the heads the intake has a lot of Carbon. What I was wondering is does meth really help prevent it? I have an AOS but I want to have very little to no carbon buildup without having to walnut blast.

NX Intercooler Sprayer Kit - $200 - Bottle, TMIC Sprayer, Solenoid, SS Braided Line. All you would need is some 16g wire and a switch. Coolingmist Water/Meth Kit -$100 - Pump, Resevoir, Plumbing, Solenoids. OEM BCS 2004 WRX - Make me an offer OEM Stock Intake[3pcs] - SOLD OEM...