You distinctly said "high power", and referred to a Lux3 as a retrofit. WTH?
You aren't going get 200lumens of amber from a 1watt LED, let alone a 3watt, and the oddball higher wattage ambers from LEDEngin and Satistronics are so horribly inefficient to the point of not being worth the trouble. Let along trying to figure out how to power them.
The only practical alternative is to use a triple star / Rebel, and redo the housing. Otherwise, what you're asking for doesn't exist.
Sorry Blastrerman I think perhaps I'm explaining this wrong. Take a look at post (# 4) I am currently using 3W Lux3 star and I want something brighter, I am in no means constrained to 3W. I need something brighter be it a 3W, 5W, 10W whatever.
Efficiency doesn't not concern me that much, this is for the turn signal on a car not a flashlight. As long as I don't need a boost circuit and I can power the driver within my available 12v this would be ideal.
The Santronics one could work but I don't think it will fit in the current heatsink. Would the 5W Santronics one be any better then the 3W Lux you guys think?
Here is the application (Turn signal bulb from Elef) I really need a LED with a dome similar in size to a typical star mounted. Which at this point looks like the LedEngin 10W is the only option so far.