I've got a lighting kit I installed on my bike forever ago and I really love the color, glow, placements etc, but it'd be really cool if I could add a fade or pulsing effect to it. Are there controllers available that I can just splice in to my existing setup that would add this ability, or does it require a different "type" of LED, and I'd have to swap my whole kit out?

 

I got mine from www.ledglow.com and their controllers have 5 different strobe settings, a breathing pulse mode and 4 dim settings.
I paid $100 for their 12 strip kit with plug and play controller controlled with a remote.

I'm sure you could grab a controller from them and just splice the existing kit into it (If you don't mind quite a bit of splicing).

Edit: here is their controller for $26.99 http://www.motorcycleledlights.com/r...ss-remote.aspx

 

Ditto on LED Glow. I have installed many of their kits and found them to be of good quality. I have had issues with their recievers a couple of times and they honored my waranty any time there was an issue.