the rule of thumb (as I understand it) is as you increase boost, decrease gap.
I'm tempted to agree with your mechanic
think about what all is happening in any engine when it's running, and then extend that out to include a turbo.
when we adjust the gap on a naturally aspirated engine, we're essentially adjusting engine timing - how long it takes a spark to jump the gap. add in a whole bunch of induction complexities and you might mess some (expensive) things up if you take them too far in the wrong direction...if it keeps running at all, which is another issue entirely, right?
If I have my information correct, you've installed a grooved TB on this engine. what are your results so far? where else in the induction system could you place a groove for the benefits - the turbo intake? the turbo outlet? intercooler outlet?
The following user(s) said Thank You: Michael Lee, CLAUDIO CORDOVA