Originally Posted by mtbkym01

So these Extech's are Sirio based? I've just commenced break-in of a Sirio Kanai Evo4 STI, with Sirio 2056 (bat pipe) and am extremely impressed so far, and would like to run a similar set-up in my ST-RR. So if these engines are Sirio based, I'm also guessing the Big Boy pipe is also the same or similar as the Sirio 2056.

Cheers