Aquamist HFS-3 and MINI Tank GB

[BostonR56S]

So, not to go WAY off topic here, but, I was at my brother's mechanic (they're pretty close friends, free labor close). Hes a ridiculously good audi mechanic, and is very knowledable about cars overall. I figured after my car sat for a few hours i'd have him give it a listen since I have the clacking (what I thought to be the lifters) when the engine is cold coming between cyl 2/3 (NOT timing chain tensioner, i've had it and its been fixed). Anyways, he gave it a listen and immediately pointed towards a dying HPFP. He says he's heard the exact noise before and thinks thats what it is. After saying how MINI has extended the warranty on them, he was pretty sure his assumption was right.

The on topic portion of this is I brought up the stumbling on cold start for the first 20 seconds of driving, and he thinks it can certainly be attributed to the HPFP not performing correctly (dying) while cold. This was my initial assumption before everything, but kind of slowly forgot about it since I hadn't seen the effects people have talked about with longer crank time/bad idle etc.

Side note also, check valve has seemed to stop the dripping.