Originally Posted by Patricius
Can you post pictures of your kit side by side with a GP Thunder 7500/8500k car? Visually I don't see a difference in brightness on your kit, and for 15x the cost, I'd hope there is much more than a marginal difference.
GP Thunders aren't even in the same ballpark - it's simply a colored bulb. Here's a diagram of the fiber path used in the e92 setup:
The inner lamp will always get a direct shot from the bulb (H8). However, the outer projector will always be weaker due to the travel path needed in the fiber lines to illuminate the ring. This is why the outer rings are always dimmer than the inner.
All the latest and greatest bulbs on the market will not correct this design. This includes HID based kits.
The AiB kit properly directs the LED source evenly for a bright uniform white light between both rings - as the vehicle should have been equipped from factory.