Piston rings?
 

How hard is it to change piston rings? Could my cylinder walls be scored too? I switched to a 20w oil and I noticed a HUGE difference. B4 I could barely pull from neutral and took 5 min to get up to freeway speeds.

From what I understand, it's not too hard if you have the right tools. But you need to hone the cylinder walls when you get new rings. And you have to mic out the cylinders to make sure they're still round. If they're out of round, you have to rebore the cylinder and get oversized pistons and rings. It can become an expensive endeavor. (I know, because I just had the same issue...)

20w oil will put unnecessary strain on your oil pump. I would go to 10w30 at most.

There are other treatments you can add to your oil to increase compression. But first, you should see how bad the compression has gotten.

Get your oil changed back to something like 5w30 or 10w30, then have a shop do a compression check to see what the numbers are. Then have them do a leakdown test to see if the compression improves. That will give you a good idea of how worn the rings are.

What is a leak down test? Pressurize the cylinder... Come back 5 min later an see how much its "leaked down"?

DIY leakdown. Ignore the part about taking off the valve cover. That's unnecessary.

** How To - Leakdown Test ** - Honda-Tech