Some explination is available here if you want to take the moderators word for it.
http://www.candlepowerforums.com/vb/...-bulb-for-9004

http://www.candlepowerforums.com/vb/...52#post3133352

dada1234
The problem with 9004 is that its low-beam is only 45 watts, compared to other types (H4, 9007, etc) that have 55W low-beam. Obviously this makes 9004 weaker than the other bulbs.

-Virgil-
Moderator

The problem is the transverse filament. Sure, the wattage is lower on the low beam than on other low beams, but the main problem is that it's hard to get a decent beam pattern.

A higher wattage low beam filament means a brighter horrible beam pattern.

See this post: It's a three page long conversation about 9004's
http://www.candlepowerforums.com/vb/...52#post3133352



-Virgil-
Moderator

The 9004 system was engineered by Ford with heavy priority on low system cost and long bulb life. It's very difficult to wring good performance out of it unless you have a very large headlamp (such as the giant ones on the '86-'93 Volvo 240) and even then, you can't get anything resembling precise beam focus.

The best 9004 bulbs are the GE Night Hawk 9004NH and the Philips VisionPlus 9004VP. Amazon.com has the Night Hawks on sale.

Avoid Sylvania Silverstar, Wagner TruView, PIAA, Hoen, and all other brands of blue-glass "extra white" or "xenon matching" bulbs. They are a scam; despite the advertising hype, they reduce headlamp performance rather than increasing it (because the colored bulb glass blocks light that would otherwise reach the road).

You would also want to put in heavier-gauge headlight wiring with relays, to feed full power to the bulbs. There's another thread with info on that topic over here.

 

I don't see a mark on the bulb, but the Hella packaging indicates that they are German.

 

same lenses..
no, no part number and that was on purpose. i have been in mexico for the last few months and found my bulbs here... no USA p/n on the packaging and even aside from the quality issue i wouldn't ever recommend anyone take for granted that any foreign bulbs they buy would even be legal in the states... but they'll work until i get home and then i'll try out the nighhawks or LED's

i will say though that i have no problems with light scatter from these bulbs. the beam is very well focused... even better cutoff that the old ones i'd say. i've looked at them straight on and from various angles. no complaints from oncoming traffic either.

 

I hope you only installed over-wattage bulbs on stock wiring temporarily to test. I strongly advise against using over-powered bulbs on stock wiring because it will shorten the life of your dimmer-combo switch contacts, and could even cause a fire.

Concur