So, does it make sense to replace the stock reflectors in my JK? The stock bulbs are dim and all the previous info is very helpful but do the reflectors also make a big difference? Also, forgive my ignorance on this subject but, what is the difference between an H13 and H4 and what are these designations referring to?
H13s were invented to meet a cost-cutting mandate/request by auto manufacturing bean counters. They've got nothing going for them. Period.
The JK reflectors aren't very good. They feed their H13s with pulsewidth modulated dc current that ranges from 4.6v to 12.6v; the bulbs are rated at 12.8v and never get there.
Bad bulbs, bad reflectors, bad power.
Bad lights.
Bad Chrysler.
H4 bulbs are better in general. Different connector, more metal, more applications, more competition in the bulb and reflector market. More choices.
You can get ECE (European) lamps and be legal too. Neat.
The connector is the same as PAR-56 for shopping purposes.
Best H4 reflectors:
Cibie & Koito
Also rans:
Hella ECE
Coming along:
Delta
Meh:
KC, Round Eyes
Not worth it, not even legal:
IPF
For bulbs, stick with Philips Xtreme Vision or Xtreme Power, especially if you are using an H13 to H4 adapter and not modifying the wiring.
If you run a full bypass harness, fused and relayed, caps and resistors, you can safely run "big bulbs" like the Osram Rallye 65/70; the bulbs won't last as long but you'll have a crap-ton more light.
Get Cibie, Koito, bulbs, harness, etc
HERE. Dan is sometimes difficult to get a hold of but he literally wrote the book on automotive lighting.
Get Hella, harness, other lighting goodies
HERE. They make every harness custom so you can add trips and dongles to trigger relays for driving lights very easily and safely. Protect your TIPM; don't burn up...
They also sell the best legal headlights there are for the JK, the Hella 90mm modules, H9 and HID. These two are not cheap but they are the best.
Want LEDs?
I put some good info in here:
http://www.wranglerforum.com/f274/has-anyone-purchased-the-new-quadratec-led-headlights-853578.html