If you are wondering which OTK bars you need to buy to make sure you will be in the scrutineers good books this year, see below!
2013 or newer OTK chassis with M6 or M4 bodywork:
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2012 or older OTK chassis with M6 or M4 bodywork:
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All bumpers are listed on this page: http://www.spellfame.co.uk/cgi-bin/sh000099.cgi?REFPAGE=http%3a%2f%2fwww.spellfame.co.uk%2facatalog%2fNose-Cones.html&WD=viper&PN=OTK_.html%23a2614#a2614
If you are having difficulty finding the viper bar, for some reason Spellfame do not list it under the OTK > Bodywork category, only under "OTK spares for Tony Kart > OTK Bumpers Front & Rear".