The 450 SX is a single cylinder 4 stroke, so no you do not mix gas.
That's something you need to check with a qualified KTM shop about.
KTM recommends Motorex Power Synt 4T 10W50
ktm 450 sx
1.35 L
Got this off of KTM talk, 44HP for a 450 exc.
The KTM sx is fast but the yfz is the best for what I do, what kind of riding do you do?
YFZ 450 WILL SMOKE It
A 450 shoud be 90 to mid 90s
The 2007 KTM 450 EXC produces approximately 50 horsepower. This power is generated by its 449cc single-cylinder, four-stroke engine, which is designed for off-road performance. The bike's lightweight chassis and advanced suspension contribute to its agility and handling in various terrains.
The 2004 ktm 450 EXC has 48Hp
around 80
ktm 450sxf