gen3 vs gen4 DBW

[400Horses]

This is just a theory, but wanted some input from those that have had more time with tuning. This is what I have going on. 2003 Tahoe with a stock Gen3 4.8 DBW. I am upgrading the 2003 from the 4.8 to a 5.3 that will be getting a full rebuild with full bearings, tsp cam, headers, and transmission. I wanted to ask about what I should do for the DBW Throttle body (I also have an 08 tahoe that has a 5.3. Do I leave the stock 4.8 settings for the Throttle Body to start tuning, or is it possible to use the 08/5.3 TB settings to setup the initial tune for the increase in Cubic Inches and Cam to help with idle characteristics?

This is just a thought I had. It may not work because of the way HPT is setup for the different generation pcm/programming, but I thought I would ask.

[blindsquirrel]

Hasn't it been dyno tested to death, and every time it turns out that for typical hot(-tish) street stuff the difference between the Gen3 78mm TB and Gen4 87mm is like, four or five horsepower?

Just use an adapter to put the 3-bolt Gen3 TB onto the 4-bolt Gen4 manifold.

[400Horses]

I'm not looking to do an intake swap or a spacer. The 03 tahoe has a new throttle body, and I will be using the original intake. I am building a 5.3 longblock and swapping the intake over, but wanted to ask because I haven't done any tuning with a DBW setup. This is also the first time I have dealt with a change in CI. and I was curious if it would work because I already have the DBW 5.3 that I could use as a reference. If its not necessary then I will leave the stock 4.8 base tune and make the adjustments like I did for my truck. Thanks for the input.

[blindsquirrel]

Yes, just tune it. No, copying in throttle settings will not compensate for the engine changes.