First of all, you guys who run high meth mixtures know you're taking a risk. But honestly, no offense but you're all idiots for running push fittings and the windshield washer reservoir. I'm getting a 335i again in the next few months most likely, and I'm going to show you what a proper front mounted meth kit should look like. I've drawn up the plans a year ago before I totaled my car but the tank is very small, serves its purpose, will require filled frequently, will be safely on tap for a couple highway pulls, but it will be a self contained unit in the driver fender. Custom built tank with the pump mounted at the bottom of the tank with the safe injection or equivalent all plumbed into the tank using entirely -an fittings and the hose to the charge pipe from the driver fender will be all of 1-2 feet long and won't pass or cross any hot parts.
Stop using cheap plastic push tubes and stop mounting your meth kit on the hot side of the engine.... At least use an fittings, braided lines and mount it in the trunk. Just because push fittings work on your Subaru doesn't mean squat here. And stop running 90/10 80/20 if you're going to use the windshield wiper reservoir.