hyper 21 8 port engine

[jimmy]

I just got my Hong Nor x1CR from ebay, came with a hyper21 8 port thing. I have only had one engine before and this is a bit different so im not even sure what I am looking at.

Basically there is an additional bit of fuel tube which exits the side of the body of the engine - and re-enters at the backplate !?!
I've not seen anything like this before (I'm a noob) is this usual and what is the difference ?

the box for the engine says "with boost attachment" ... So I guess that is what it is ? whats it mean, and is it bad ?