I presently run the EZ with my 2s. It's a great combo, and the bottom end has serious girth. I can run this combo with the EX set on most aggressive and easily control the smoke (even here at 6000+ ft elev).
That's why I am thinking about Mach 4s, and then just switch down my EZ. So far, large injectors have proven to be a lot more streetable than I thought.
When/if I upgrade to a fueling box, I will NOT stack the two. The timing advance caused by the installation of large injectors means that the EZ and PMAX would probably be a little too much.
Thus, an upgrade to a wire-tap box would be a TST alone, for me.
The newer TST boxes DO have a timing element to them-- but it's a lot more subtle than the Edge boxes.
Personally, I think the TST is the best box going. It tends to run hot, but it's controllable.
BTW-- my stock clutch still holds very well, even with the EZ on grunt, and the injectors.
If you start out in 1st, the stock clutch can often hold a lot more power than people think. I am 350ish and have no slippage at all.
Justin