I have a Blitz Nur Spec R, decatted on my Evo, Very noticeable when cat and bung fitted for MOT.
the performance with the bung fitted itself is noticable as well, not massively but it is noticable, which i fit for the journey home from camp(210miles) as the Evo can be a tad on the loud side without it.
last time i made that journey i didnt bother as i was in a rush, my hearing was dulled and ears were ringing all night after getting out of the car
which reminds me i must get a decent video of it on gear change at ful chat and overrun, bangs and flames are fun