J-Rod

Corvettes are DBW. We have no IAC. The TB blade is our IAC. So, we use our TB to control idle with no other interaction. I don't drill holes in the TB, but I have seen people that do. I know first hand you can tune VERY large cams to idle just fine without having to drill.

Drilling the TB is just the same as drilling the throttle plates on a holley carb to be an airbleed. Some folks swear by it, others disagree with it. My personal belief is to use the IAC motor and the TB. Once the hole is too big, you're done with the TB screw adjustment you can tweak till its spot on...

2xLS1

iTrader: (25)

The drilling holes in Holley carb plates is not exactly the same comparison. That is done to not expose the transfer slots in the baseplate by opening the blades too far. Our TBs don't have transfer slots. I also think it a little unfair to compare getting a DBW car to idle without drilling a hole compared to cabled TBs with IAC motors. Those cars calibrations seem to be able to get by with TPS openings of 7,8,9% at idle. I have found that once you go above 0% TPS on cabled TB cars, you introduce a lot of other problems even if you do the TPS reset procedure as the actual TPS voltage will still be too high. Here is a quote by another expert from the link I posted about adjusting the set screw.
Originally Posted by KEN @ HP Tuners
That is the exact reason to leave it alone. There are over 5000 parameters in the VCM. Not everything you can adjust that sees the TPS is in the editor.
You will just wind up screwing things up.

gillbot

iTrader: (27)

That was the problem on mine, no matter what I tried the TPS position would NOT go to zero with the reset procedure and the car would idle messed up until I put it back. I'm guessing it was still reading an elevated TPS voltage and getting confused.