I would have to agree with Ant here. I made my own grounding kit by replacing all of the thin and worthless strap grounds with solid high strand 4G cable. I instantly noticed a smoother idle and a smoother powerband, but no actual power gains. Also, like with Amy, my lights stopped dimming under load.
If you REALLY WANT a grounding kit, here's what you do...
Go down to your local audio shop and purchase about 15ft of 4G wire in your favorite color, and also get some 4G ring terminals that have a 5/16" hole. go home and start replacing all your crappy straps with your nice new 4G. It'll cost you about $20 most likely, depending on who you get the stuff from. If you feel like shopping online, I personally recommend a company called Knu Konceptz, they have great wiring for a great price. Their eKo series wire looks great and is cheap, though its only available in Blue Metallic and Silver Pearl. That stuff in 4G runs i believe 79cents a foot, which is very well priced. actually, i'de say just about everything on their site is very well priced. That's who i used for my entire system, and that's who i use for all of my customers as well when i'm doing installations... Top notch stuff...