Upgrading the coil pack on your SPI can give you better throttle response, more power, and maybe even better gas mileage (if you don't get lead-foot-syndrome from the benefits of it!) FlaFocus shows us how to do it!
Unless you have a pre-modified mustang throttle body, you'll have to modify it before installing it on your SPI Engine with an adaptor plate. This is how to tweak it.