Hi Guys ... I've looked over a lot of the threads and i find some vague references to the '05 WR450 muffler and i was wondering are there any modifications worth doing to get similar performance to a GYT-R or FMF pipe? (short of replacing it and spending big $$). I've heard of hollow coring it with good results but these reports have always been the 'friend-of-a-friend' kind and i have no real first hand information. It seems a shame to replace it because the basic design, casing, style etc are all there to begin with and it shouldn't be too difficult a modification ... your thoughts please ?