I dont know the part number off hand but im sure I can find it out for you.

I used them because they are tried and tested and readily available, and when I ran the idea past Stu @ MSD years ago when I first did it in about 2005 or so, he said that he also had used them with good success on things like RS turbos, so that seemed like a good endoresement.

We use them in quite a few engines in the vauxhall world now, Rob's astra also has them for example and thats certainly taking a massive beating for a home made effort!