The European EXC versions have a small headlight, speedometer, tail-light and somewhat softer linkless (PDS) rear suspension.

The factory RFS (Racing Four Stroke) KTM 400 EXC won the 1999 World Enduro Championship.

While others used a 90mm-plus bore piston with a very short stroke of 60mm, the KTM RFS motor used an 89mm x 64mm boiconfiguration which provided more torque at the expense of higher RPM's.

The conversion of the previously available model required changes in gearing, exhaust, DOT approved tires and lights and the addition of turn signals, and a horn.

[5][6][1] As of 2008 the US version of the 450 EXC continued to be sold in street legal trim but was replaced by the off-road only 450 XC or 450 XC-W in the US market.

New features include new front Brembo brake caliper, PDS needle design, frame welded to steering head 10mm lower, reinforced gearbox (1,2,5,6 idler gears), reworked chain adjuster & clamping rail, better tension on timing chain (noise reduction).

For 2012, new features include EFI Fuel-injection, a diaphragm spring clutch and a lighter battery.