I recently bought a 5500c

[coastalobsession]

I was wondering what kind of upgrades are out there

[akfish]

The only one I'd recommend is a set of Smooth Drag Carbontex carbon fiber drag washers with Cal's grease, but only if your reel is a few years old and doesn't have carbon fiber drag washers already. The new ones do. Some people put ball bearings at the ends of the worm gear to speed things up but I don't think that would make any difference to me given my casting skills.

[Keta]

If it is an AR bearing reel you can add a AR dog and a larger handle is is nice.

[coastalobsession]

Carbon fiber is a givin. I put a power handle on my 6600 and when I Crank and
let go the spool jumps the tracks and makes a clicking sound

[0119]

Ceramic pawl.  Dual ball bearing levelwind.  Ball bearing idler cog.  Ball bearing on the gear shaft.  Ceramic hybrid Abec 5 bearings in the spool.

[Ken_D]

Carbon fiber is a givin. I put a power handle on my 6600 and when I Crank and
let go the spool jumps the tracks and makes a clicking sound

It will only do that on the bench. You are hearing the pinion jump up and down on the clutch of the spool, and that's because the spool is going backwards, relative to the pinion, so the pinion can't engage the clutch.  Not really an issue, just what was that !!!  when it happens.

[alantani]

yes, that is normal.