Water/Steam cleaning inside of I5s

[David]

I'm talking about cleaning the INSIDE of the enine with steam...to remove carbon and gunk. I've done it several times on the SBCs but never on any of my Audis. The basics are:

1. Start and drive car to get engine nice & hot.
2. Pull an intake vacuum line  and put it in a small bottle of water (distilled) while engine is reved to at least 2,000 RPM (if left at idle it will stall).
3. Let her suck in the water. It will vaporize into steam before entering cylinders. 

The engine will cough and sound terrible and TONS of black smoke and carbon crap will fly out the tail pipe. It really works well.

But my question is...which vacuum line is best to use on our cars? Anyone BTDT? Any words of wisdom or caution?

TIA!

Dave
1987 Coupe GT 2.3
SE Virginia