I'm going to get an '89 Sidekick in the near future.  How much power do I lose if I put bigger wheels on?  Can I solve that problem with re-gearing?  How about if I do an intake and exhaust?  Bottom line is that I want to go bigger, but don't want to sacrifice power.  Is that a pipe dream?  

First of all, Welcome to Zukiworld!

How much bigger are you thinking of going?

Would it be a manual or auto?

Cwkick

OK - first, you won't have much power to lose in the first place!  Hopefully, the 89 Kick has a 1.6L engine, and not the 1.3L engine [EEK].  Yes, you can regear it all the way to 5.83:1 Ring & Pinions (and I highly recommend it).  The only way to change the "hi gear" gear ratio in your transfer case, is to replace it - for instance, with a Samurai (divorced) tcase - that's a lot of work!

Put a header and cat-back hi-perf exhaust on it, and put a K&N air filter on the intake side, and you'll get better performance.

Let's see:  Stock tires are 27".  You can go to 29's with just a small body lift, I guess, or up to 31's with the Calmini 6" suspension/body lift, which I also highly recommend.

If you want to cheaply fit 31's, a Calmini 3inch body lift and sky's 1.5" coil spacers will do.