I bought a Delkevic Mini 8" 200mm slip-on for my Kawasaki ER-5 (link: http://www.delkevic.co.uk/?section=s...1996-2007_3209)

I needed a new one as the stock exhaust has rusted through and makes a horrible whistling noise in colder weather, and this is the only one I've seen for an ER-5 that wasn't stupidly expensive (the only other make being a Fuel exhaust, which were slightly more expensive and didn't look as good in my opinion).