Level Ten is the only place I know of that makes aftermarket TC's for the CD4E.
The stock TC stall is around 2250 RPM. As you might guess, that's a lot lower than the Duratec, or even Zetec makes good power. Depending on what you want this stall converter to work best with, you have a range to mess with. For drag racing, you might want to have it as high as 4000, but you need to keep "streetability" in mind. Too high, and you're revving the crap out of it from a stop light.
For driving and occasional trips down the quarter, I would go for a 3500-ish stall. If I was going to drag it more, I would go up to 4000. Anything higher and you'll think your tranny is broken.
