The manifold socket is 12mm, and I'm not sure the brand. They are only marked 'Taiwan" and I'm sure it came form some cheap set I acquired over the years. I think being 1/4" drive and light duty is the reason it's so thin. You might try putting one of your sockets on a drill or impact and sanding/grinding the outside diameter down a bit to get it to fit. If nothing else, I'd be happy to ship mine down.

I'm not familiar with those downpipes, it would be interesting to see how they fit. The price is definitely good! The driver's side upper O2 sensor and shift linkage are very cozy with the stock pipes, so hard to say if the aftermarket pipes would be better or worse. I kept the stock pipes and gutted the pre-cats, which is generally accepted to be good enough for stock turbos. Gutting the pre-cats necessitates the O2 cheaters, and the placement of the sensors on those ebay pipes looks like they need the cheaters as well.

And Yes, Alex is the right tuner, you are in good hands with him.