ive been running el coil pack on my car with leads for some time now, spark jumps as far as the grand canyon, its up to you. spend the $500 for a bolt in coil pack that looks neat and can run std dwell, or bolt in a diff pack with leads and run more dwell= bigger charge and greater spark therefore better burn and more power is made, they f**kout due to the heat from being bolted to the cylinder head, i can guarantee you mounting it on the firewall would be not as hot for the coil. ive seen the el pack on rb26 t88 make well into 700bhp with no issue's std ignitor. however this was dyno time only, dont know how long it lasted this way.