I was enquiring about purchasing a new coil pack for a MY94 STi RA, the guy said that from his experience it's worth replacing all the coil packs at the same
time, otherwise i'd be replacing them every few hundred miles as they
break down. Would there be any truth in this, or is it just a ploy to get me to buy a full set of coil packs?

 

best to get full set as they usually are all cracked on the end that joins to the spark plug, mine were!!!