Someone private message me concerning
my front signal LED which I claim (above) to be brighter than OEM incandescent, the LED is Amber only and Not a switchback. So here is a short review:
Amber LED 7440 W21W T20 21x 3535-SMD CREE
Total price I bought AU$33.94 (from ebay Hong Kong seller, China)
Note I am not sure if the advertiser is truly selling CREE, indeed the LED is incredibly bright even in day time, it is definitely seem to me it is much brighter than the OEM incandescent!
The only drawback is the Amber/Orange colour is Not as golden as the OEM incandescent; I doubt if there is any LED colour is as good as an incandescent globe, from my experience LED just don't have as deep and good colour as incandescent; it is same as in LED TV or monitor comparing to older technology such as cathode ray tube TV and/or plastma TV; LED just don't have that good colour variety and scale of depth (black, grey, etc).
Nevertheless as I mentioned before OLED or AMOLED (like on mobile phone, e.g. Samsung) will match and give out incredible depth and colour, its colours are incredible, one day on our TV then I imagine OLED will come over to all other uses including OLED lights for our cars. 
- 1st group of photos show left OEM incandescent vs right 21x 3535-SMD LED
- 2nd group of photos show 21x 3535-SMD LED different angle
- 3rd group of photos show similarly
- 4th photo shows its brightness on the car, note flash-light is used to reveal the surrounding yet its yellow light can still be seen on the ground.