You get the "jump" in horsepower from the decreased resistance of the chassis. The chassis might have a resistance of 2-3ohms, while doing a strap straight to the battery would have .5 or so ohms. That little decrease in resistance causes your voltage or current to go up ever so slighty, all dependent upon what type of metal the manufacturers use, how thick it is etc etc. (No I don't know which cars are more resistive than others, and no its not a big deal). You'd do just as well to go down and buy a spool of stainless braided bonding strap, and terminal lug kit, and do it yourself.
Don't hold out any prayers for horsepower though. I think its silly that companies like HKS are treading on APC's engine dressup (the only tangible benefit you'll get from all this) territory.

 

SCREW APC, let each do there own and whatever company comes out with the BEST product wins.

 

i can make my own. i can get quality wires and crimps for less than the $100+ they try to charge.

if you can do the wiring in your cars audio system, you can do this.

 

in my opinion that money spent on the 3hp can be better well spent on something else thats just my 2 cents

 

I went to a car stereo place, and got like 12 ft of 8 guage wire for 5 dollars. The just go get some connectors for around 5 more dollars. So the whole thing should cost you like 10-20 dollars maybe

 

for real