Should - the G2 ('99) and J2 ('01) should at least fit the same. Most exhaust companies show the same part number for '98 to '02 for the bolt-on cans. While the engines were redesigned in 2000, the exhaust systems shared at least the same dimensions and fittings.
Two Brothers for one shows the same part fitting 1998-2002 even for full systems, as do Akrapovic, Micron, Yosh, Hindle, and others... however Kawasaki shows two slightly different part number extensions for the stockers (#18090-1820 for the 2001 and #18090-1666 for the 1999... although likely on the exact same part). Muzzy also shows a SLIGHTLY different part number for the two years.
If in doubt, look up the part number for the brand of end-can you're looking at and find out if the same part fits all those years.
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