Shredicus
Dedicated LVC Member
What do you mean by harsh shifting? Delayed engagement? Abrupt engagement? Delayed would point to the solenoid pack.
When running regular the computer will retard timing to prevent pre-detonation, or "knock/pinging" resulting in poor performance and lower MPG. The money saved per tank is more than lost on the lower MPG.
Ah yes, one of the few times you'll see the word "retard" used one an internet forum not as an insult.