That's something you need to check with a qualified KTM shop about.
Mid 90's stock.
got mine at 99mph
The 450 SX is a single cylinder 4 stroke, so no you do not mix gas.
ktm 450 sx
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?
KTM 50 tops out around 50-52 mph my 06 ktm 50 hits 55-60mph
According to the 08 KTM Tech Bulletin, .3L of Motorex Top Speed 4T 15W50
A 450 shoud be 90 to mid 90s
YFZ 450 WILL SMOKE It
The 2004 ktm 450 EXC has 48Hp
around 80