I am putting together a 1 liter for my wife's Metro right now, and I am going to try the grooves. Unfortunately, I bought the car with most of #3 piston in the pan, so I won't have any data to compare. I found a post that backs up most of TELVM's claims, especially the reports on oil cleanliness - Link is under post. BTW excellent work, TELVM.....that is probably one of the best looking SG jobs I have seen. I'll post what I find out after I put some miles on it.
Singh grooves in cylinder head - Speed Talk