[Chris Williams]

The problem with stops that control the throttle cable/line is that the line and the parts are flexible, meaning it's tough to get consistency run after run. Under-carb stops are built from a heavy billet piece and go to the exact same spot every time, regardless of the pressure you have on the pedal. Some people put a very hard stop (bolt or something) under the pedal to insure consistent pedal pressure, but to me that's a band-aid to make an in-line stop work.

Discs are better because they are more directly proportional. Imagine a 25% closure of the disc, and a 25% closure of the traditional blades. If you close it by 10% more, a disc limits flow by precisely 10%, but blades don't -- because the angle changes, some slips by at a higher rate, it's not exactly clear what 10% more is because of the angle, and the actual rate of flow changes. In all it's not exactly 10% more.

IMHO, the best stop on the market is the Dedenbear TS6. It's just a rock -- highly predictable, highly consistent.