I have checked into the difference between the 385HP and 403HP engines. From what i was told on Hp Tuners the difference is in the tune.
This is from Hp Tuners forum.
"Comparing several stock 07 Yukon and 07 Escalade files only one table I see different that would account for any HP increase in the Escalade are the values in this one table. The pic shows show how much less timing the Yukon has in PE mode vs the Escalade and only at 5200 rpm and higher. All the other timing and fuel tables are the same. Most tuners would zero that table and tune the main spark tables for performance anyway"
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