Hello, I have just tried Sirio Evo4 on Melzo (Italy) track, where Sirio Official Team tests and develops engine and where I run.
I have used in the past Sirio Evo3 and Evo3 Sti, but according to me Evo4 is the best, it's really fast!! Now there is a different steel bearing instead of Evo3, and if you want you can also use a ceramic bearing made by Sirio.
About pipe, Sirio sells now a new edition of Efra2611, you can see in picture the difference, it's stronger.
About glow plug, there isn't in the box with Evo4, but use n7 for best performance!
If you need other informations, also about purchase, please be free to contact me, no problem!