I have a 1300 Felica Endurance Rally Car. The coil pack failed before the last event and it was replaced with a Standard Dealer suplied part. The car is lacking response since.....is there a modified coil pack available.

I think you need to look elsewhere. There's only one coil pack available to my knowledge, but it sounds like you have another fault, rather than it being the coil pack (unless, of course, the new one is faulty, which is possible but unlikely)

It's worth checking the output from the ignition LT circuit to the coil pack too, Its not unheard of the ignition driver circuit in the ecu to fail Or become erratic after a dodgy coil pack has short circuited it