One of THE biggest issues I find when helping folks with their combos is the converter fall back. Most guys think 15-1600 is fine, WRONG! Thats outdated antiquated thinking on the subject. All that is going to do is slow you down. Every combo is different for sure but anything with 4 digits of fallback is going to be to much. In my experience "loose inefficient" converters tend to be fast. If you are looking for an ultimate low ET then thats they way one should lean. Companies have gotten much better at making loose converters more efficient in high gear for sure. We even have a lock up option now. In the heads up car we like to see 5-600 on drop back. But alot of factors play into getting there, weather, gearing, tune up etc.