I dropped by Xoom last Saturday and i'm satisfied with the tune-up service they did to my kit since they utilize the 02 sensor to read the emissions and the cpu inputs tally up. No guesswork involved. Will be going back to work on the high rpm band to see if we can improve my highway consumption which isn't far off from the 10km/L+ i get during city driving.

Its also best to change oil, spark plugs and (clean/replace) your air filter prior to getting it tuned.

On a related note, I had a compression test done at Speedyfix and the compression readings came out at a healthy 175psi across all 4 cylinders. This is after running on LPG for the last three and a half years and 65,000kms (change oil every 5,000kms using Mobil 1000 mineral oil). I had a scare leading to the compression test but it turned out to be a busted radiator cap.