a slip on is a muffler. & usually a mid-pipe. $500+
deleteing the cat, NEED a PC3 & lose weight off the bottom (not as good as
losing weight off the top) free-$75
gutting the cat, not much weight to lose, freer flowing, still need the pc3 & might take more time for the welder.
full system - tuned header, available in ultralight Ti usually either 4-1 or 4-2-1
^ $1000+
for a few HP. on the top end.
but, with a freer flowing exhaust & a proper FI tune flames are possible & don't do much damage if any & is caused by running rich. but, there are other flames caused by off-timed ignition that CAN hurt the engine.
mine pops small flames at partial throttle @ mid-high (10-12k) rpm. no damage yet...
my bike (after jumper mod) outran an '08 cbr600rr with a Ti jardine.
$700 down the drain.
jardines look better on kawi's anyway...