I know this is an old dead thread but I was wondering what the pros / cons of a spacer are. I want to stay as stock as possible (besides cutting the fenders) and just want a little bit better stance without sacrificing ride quality or spending a ton of dough. Is this the answer?

The stock XJ springs are the softest spring rate available. If you just want a boost and aren't adding weight a spacer is is a good choice.

The con is that you are shorting your front bumpstops.
Not really a big deal because there are ways around it.