The cable is from Cablecraft (
http://www.cablecraft.com/). Morse is another popular brand of push-pull cables and are more readily available since a lot of boat shops stock them, but the cablecraft cables are a lot more flexible. I don't remember where I got the throttle linkage but r.d. enterprises sells similar ones. The linkage has two return springs you can see in the lower right of the picture. You can't see it very well in this picture but I have a small coil spring that goes around the cable end between the rod end and the sheath as an extra safety precaution.
Brian is right about the difference in the cables. I used a Cablecraft cable for the throttle cable on my race car and thought I felt a difference but I really can't say that the difference wasn't at least partially imagined. They are great cables but pretty expensive and as you can see, they're a bit bulky and so my throttle cable "prints" through the carpet a bit. I also have one for the clutch which of course you can't really see.
Why did I get them? I didn't want to go through the hassle of adding a hydraulic clutch (ok, I wimped out
) so the next best thing was a better cable. It is certainly much stronger and sealed better than the stock clutch cable. As for the throttle cable, I just went a little crazy!
It obviously is a bit safer since it is a whole lot stronger and sealed better than a standard cable but it is a bit more trouble to implement and most people wouldn't be able to tell the difference at their feet.