What kind of gearbox does it have?
One additional reason was the T5's small bellhousing that maintains good ground clearance
In my haste I didn't give all the detail about the ACE's transmission and it seems important to mention...
The T-5 was chosen for the ACE because that bell housing is smaller and it's also removeable (almost all other gear boxes today have integral bell housings). Pete then created a new minimal housing for a 7.25" Tilton racing clutch. The T-5's original 12+" dia. was reduced to 10" by making the custom housing (Mazda's is 13.75 I think). This also assisted in a lower engine mounting for low CG without clearance issues.
Sorry again for the thread drift, back to your regularly scheduled programming...