On my 97 cr I have had 3 pipes besides the stock. Originally i bought the PC platinum with r304 silencer. this was a good pipe for top end and over rev. then I got and sst and power core 2 silencer, this pipe made a little less top and over rev but more bottom than the PC. then I got a gnarly, and is pipe has slightly less top end and over rev than both the pc, and sst, but tons more bottom.
I have stuck with the gnarly becuase I love the bottom end and I think with the gnarly it is easier to stay in the power band than the other bikes. i used my bike for every thing (woods, trails, sand dunes, MX, and SX tracks) I also went with a 51 tooth rear sprocket and I have a tendancy to short shift.
I might also note that the gnarly is a tougher pipe that the pc and sst, since it is made of 18 gauge steel. (trust me it makes a diffrence as much as I crash and also the reason I have been through 3 pipes on this bike.)
I am going to go with the gnarly on my 03. :aj: