i just ordered my nelson tune 93 high perf. setup .when iwas reading through i noticed i get 2 single vehicle credits and 6 yr/model credits pr yr.what does this mean remember guys this is my first tune.i did a 4.8 swap to a 6.0 with a 216/220 525/532 cam wguide plates springs and 1.75s and hardened pushrods .so far im not impressed w ith the swap, is the tune going to make a big differrence?if so what kinda power diff.should i expect? i appreciate any input ,thanks.