Got both the sachs 2 clutch kit and the intake plenum from RSS installed a couple of days ago and here is what I found:
first the clutch, the sachs 2 clutch is an intermediate between the oem and the stage 3 clutch with the sintered disc and difficult drivability and as expected the sachs 2 is very very close to stock. The pedal is at the same height at rest but grabs slighly earlier than stock which makes it nicer to drive. No chattering or noise forward or reverse. I am very happy so far but I was told not to really test it for a couple hundred miles, so far so good.
One problem for me was to find a shop able to do the clutch job without removing the engine with the transmission. both dealers in san diego wanted to do that and they wanted to charge 17 hours for labor.
Most shops wanted to charge the same except one I was lucky to find who had an experienced tech and he did it without removing the engine, I was charged 11 hours for the clutch.

As for the plenum, most of you know that the car has a cargraphic loud exhaust, BMC filter, upgraded VTG turbos with larger compressor wheels and an ecu tune to go with that cocktail.
I tried to drive the car hard for the first 50 miles or so but it was difficult with the traffic but still I noticed something that was not discussed before.
Before the plenum my car would just explode when the boost comes on and it comes on very hard and stays there till redline. The first thing I noticed after the plenum was that the explosivity of the car had slightly diminished and now it is more like a wider smoother pull from slightly lower rpm, the sudden gun shot effect is decreased which makes the car less violent and more smooth.
I did not feel any actual increase in power and don't have any numbers yet but I can assure you that it is very difficult to feel 20-30hp or even more when you're close to the 700hp level, acceleration seems similarly impressive.
I think I am drawing the line here since any more mods would probably be asking for trouble with the stock engine internals so I have decided to keep the headers and intercoolers stock, ..........for now