If you get one supertuned, you will do them all. I did my curados myself and it does make a difference. I switched to daiwa and the only gain is to change the bearings and put a carbon fiber drag washer upgrade. The way the spool set up is in my daiwas not much polishing you can do to gain anything. I love my Zillions.
Most other reels you can gain quite a bit. Polishing the friction point such as the certain areas on the spool shaft, inside the pinion gear. Friction points on main gear and key washer the upgrade drag washers make the drag system sooo much better. The other parts I said to polish in conjuction with either flush bearings and relube the ones you have or upgrade bearing. This will let cast farther with less effort or with a trained thumb you can cast sometimes 10 or more yards easy. But you can tune them too much and its hard to control them. Just have to find a happy medium. I just take the stock bearings and flush and relube them assuming your bearings are good. Polish parts on spool, spool shaft, Key washer and gears and the drag upgrade. That is the way I found to be the biggest gain. Just do your own research because there is a lot of info out there. Check this link. This is basically what I do.
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http://super-tuning.home.mindspring.com/i1.html
Polishing brake hub is very important also
Great forum I read It every day
Hope this helps