Those replacment clusters do not work. I tried them. APC (of all companies) makes almost a complete led replacment set for the Insight. I bought them and had to return them. Reason 1: They put out a uni-directional light made to be behind a diffuser like in an alteza type replacment fixture. This would have created a big hazard on the road as you would not have been able to see the brake lights unless you were looking straight on, plus the illumination was greatly reduced.
http://members.aol.com/evracr/led.jpg
The led is in the left fixture, a regular bulb being in the right. I was looking to get that led bar light intensity across the entire rear. I was wrong.
Reason 2: If the led clusters are right as they claim to meet oem specifications then the Insight does not have standard wireing. The led's had the positive ends both on one side of the cluster, the insight criss crosses the polarity across the bulbs. This is not a problem for a bulb, but on the led clusters you could say get the brake lights working, but it would short out the system and blow the fuse once the running lights were turned on.
I also got the clusters for the turn signals. They had the same problem as the brake lights, the uni-directional light did not fill the reflector at all. While the light was instantaneously on, it was only bright enough to notice looking straight in to it, which a truck or SUV will never see.
So that was my experience, if you come up with something different I'm open for suggestions. I think the only way to make it work properly would be to use a lot of LED's. You'd hollow out the rear of the tail lights and make a clear plastic insert that would fit in the housing. You'd then drill as many holes in this as you could fit and glue the led's in to that so you'd have a grid of led's, then wire. The only problem with this is a new set of tail lights is roughly $300, which is a lot of you screw it up. If I can come across a set for about $100 I'd probably have to give it a try. The encouraging thing though was with those clusters barely working, I was looking to save roughtly 3 amps per bulb!