Bottom line is the T5 isnt the greatest of trannies. When they were first designed the Foxes were making 180ish hp.

The t5 is a very light trans. Weights about the same or less than a civic tranny. Gears are very small, they are nowhere near as strong as what comes in the newer mustangs. They also got a lot of issues with grinds and sloppy shifts. It's just a very old desing is all. You can tell they are worlds apart whne you drive them and then drive a newer mustang with a t45 or a t56.