Hey, here comes a report from Sweden.
Have just done The Groove on my Toyota Avesis 2004 1.8 lean burn. I used the largest bits so it was obviously a hole, but after Ron's pep talk, about hole, it was no match to mend it. I have more power in the engine, better exhaust values and after only 100 km, I can see that fuel consumption has gone down. So everything that I expected from this modification has occurred.
Thanks Ron, this is really good.