I had checked into the relays somewhat deeply and concluded these kits are top shelf and easy to install.
I was going to make them myself , but between shipping costs and my personal time , the kits are not a bad deal.
Both vendors use the Matsushita (panasonic) relays which are the smallest,toughest,waterproof type relays out there.
The wires are equivalent to 14GA which should move 15 amps fine , we only need wiring capacity for 4-6 amps.
If one were to run 100watt bulbs , the ceramic end for the headlight connector would be the way to go for heat.
I did mail back and forth to Eastern Beaver last year , he seems like quite the enthusiast and takes pride in his kits.
Relays are on my to do list later this year , money has been a bit tight lately though.
Mick

 

Awesome comparison photos - which PIAA H4 bulb did you use for this comparison? Was it the PIAA Item #70426 "Star White Anti Vibration Halogen Bulb"?

I see the PIAA #70426 bulb listed on Amazon for $30.82