The KTM 105 is a good bike if you are transferring from a medium sized 4 stroke to your first 2 stroke. It has plenty of power. If you ride hard you might be better of going for a 125 you will be able to ride it longer.
A Ktm 125sx is not a good trail bike because sx means super cross so it is a good racing bike it is good for jumps and racing
good bike
For 2008, KTM won the 85cc shootout, however there are more things to consider than someones opinion on what bike is best. Pick a bike that suits your riding style and size. Also, it doesn't matter how good a bike is, if you don't have a shop to help you with getting parts and technical knowledge, your bike is just another bike.
yes
the ktm 105 is way faster that a ttr
KTM
i would personally say the ktm is a better design good frame great bikes the only problems are the price of a ktm is very high where as the cr 125 is a great bike for racing like the ktm 125sx are both 2 stroke and i would say the overall faster bike is the ktm but not by far both my favorite types of bike
90mph
The KTM 360 SX is still a good bike, like all other KTM's dependable but parts are expensive when you need them. Here is a link that has pictures of the 360 SX: http://www.bikepics.com/ktm/360sx/
well a ktm dealer would be a good start or you could always try eBay but my advise always test drive a bike first and give it a full inspection if your not that good with bike mechanics take some one that is
Depends on the bike.
105 mph with out modification