well, regardless of what these other folks just said...
I ground kit isnt going to hurt your car for certain, and obviously it doesnt matter if its Japanese or not, its wire cabling! Those ground kits are used IN ADDITION to the ground wires presently in the car. If you run a sound system in your car, look into the "Big 3" or the "Magic 3" ground system - its just a matter of adding a few larger guage ground wires between a few specific points under the hood, I'm not certain how much a difference it would make since the battery is in the trunk, but again its probably not going to hurt; also I would just make a few ground wires myself instead of buying a kit.
ps - I had Nissan SE-R Spec V that only had an 80 amp alternator, and doing the Big 3 ground upgrade helped increase throttle response, reduce engine noise in the electrical system, and increased volteage to my sound system.
pps - I guess you should always consider that not EVERYONE knows exactly what they talking about on the board here, search other forums too!
<img src='http://www.bimmerwerkz.com/forum/uploads/post-19085-1125500838.jpg' border='0' alt='user posted image' />
98 328i ECIS CAI / Tint 35% / 17" Gun-Metal Gray M Countour style wheels with Polished chrome lip and 235/40/17 Toyo Proxe T1-R's / Silverstar bulbs - head and fog
System - Calrion ProAudio HU / MB Quart RA 1000 Sub amp, RA 4200 4 ch amp / MB Quart PCE 213 5.25" seperates front / JL Audio VR 6.5" seperates in rear / Stinger SPDH5 Pro-Hybrid 5 farad Capacitor / Alpine Type X 12" DVC Sub in a slot ported box