I have an '03 with the 10.5 single flapper hotside, Denso 720's, 272/272 cams, and 255 lph fuel pump. I was wondering if I would be better of starting with a ROM from an '05 and using it to tune my car. I think it would be a closer starting point because of the turbo.

 

I dont think there would be any difference. however, one of the main differences i have seen with the 05's is that they have a completley different open loop load #1 and #2 tables.

 

Actually I found it in another thread. I will compare the fuel maps and see what differences there are. And I will compare the timing maps as well. I will try using the fuel and timing maps from an '05.

 

IIRC, the timing maps are the same but the High Octane fuel maps are different between the 03 and 05.