Graphfixz, I've used #7 successfully using Mike Phillips method of allowing it to skin, etc.
The comment you made about the pre-wax cleaner making the black paint go white caught my attention.
You don't give much info about the age and condition of your car but, I wonder if your paint (if old) is starting to fail in certain areas...this would explain the matt/drinking-it-up/going-white results you're experiencing. The cleaner could be building up in the micro-crazing of failing paint.
Then again, it could be something totally different. :hm
I found another pre-wax glaze that you may wish to try that produces stunning results, and that is much under-rated, IMO. I know it's not very fashionable and a simple OTC product, etc., etc., ad nauseum, but I would recommend you try Mothers Sealer and Glaze. It contains similar beautifying ingredients to #7, like polishing oils and kaoline clay, but is simple to use, dries and buffs off without effort, with an excellent cosmetic result.
Here's a car I did using Mothers' S&G, topped with S100. BTW, the finish was liquid, glossy, and deep, from S&G
before applying S100.
This is twelve year old paint.