This might help if you are replacing the housings:
http://www.jpmagazine.com/techarticles/electrical/154_0710_jeep_headlight_shootout/index.html
JP Magazine tested like 6 of em or something.
And, on the relay thing... unless you are running reallly high wattage, you won't need more than two relays. Even a cheesy Bosch style relay can handle 30 Amps, with the better ones doing 40 amps. A 65-watt high beam would only draw about 9 or 10 amps.... two of em, double it. Even if you went up to 130 Watt high beams, you are still only talking 36Amps. The better Bosch relay would handle that with no problem.
If I were to do it, I'd mount the relays to the grill on the driver's side and tap into the stock wiring there. Make sure to use some decent wires to power things... don't use the cheap parts store stuff... finer strands is better.
With a Bosch Relay, you'd wire it like this:
85- ground
86- switched positive from the Jeep harness (low beam or high beam... whichever relay you are wiring up)
30- high current draw positive (you decide where you want to tap... this is the wire that will feed the power through the relay to the headlights. Again, if I were doing it on mine, I'd use a switched positive off of an auxilary fuse block)
87- out to headlights.
And, while you were at it, you should really take a close look at what kind of shape your 20+ year old headlight plugs are... I'd replace mine.... cause mine don't make great contact, and that blows bulbs. Painless has them... I dunno about parts stores. And, if you wanted to dot every "I", run the headlight's ground directly back to the battery.
Oh, another thing... I've run 100/130 lights before in one of my Jeeps... they blow out quicker than the lower wattage units. I think its because the filament burns hotter, and as a result is more fragile. Couple that with the vibrations of the Jeep and it resulted in a lot of burnt out bulbs. The 90/100s were a nice compromise between blowing all the time and crappy lighting.
Also, if you are going with the higher wattage H4s, you might not want to use the regular crimp connectors at the relays, and instead get a relay socket... looks like this:
http://www.tessco.com/products/displayProductInfo.do?sku=465687&&source=Froogle
I like the ones that have the wires coming off already. The issue with the cheap crimp connectors that crimp to each individual wire is that they don't actually contact that much of the terminal on the relay. Long story short, I've melted them with prolonged 130W high beam usage. For a few more bucks, go with the socket for the best connection to the relay terminals you can have, short of soldering it on.
