Well the exhaust is restrictive now so a bigger one is needed, the kw's were going up with more boost but not by much cause its choking so instead of stressing it out for every last kw, Yavuz made it safe enough to hammer everyday and turned the boost down.
Also, its pretty much quick enough for street duties as it is so why bother with more. Ive pretty much done what i set out to do on this motor, if i find a nice 4" exhaust thats another tune
Your fuel system just wont cope, ID's