Alternator wire modification question

[BIRD]

Hello- I have done the alternator wire mod from the How To Documents, works great with the John Deere HIR 9011 bulbs. I have an aftermarket stereo with Sirius Sat. Radio and amplifier in my 92 LS Pearl. My dilemma is, now that the weather is warm here in Boise, ID, when running the AC I get the whine associated with poor grounding through my stereo. Stereo installation was completed by a reputable shop in town. The amp is grounded to the chassis in the trunk, and the alternator mod was done exactly as shown in the write-up, with nice audio 4 gauge wire and great connectors. Everything is quite snug. Can I get away without the 2nd wire in the write-up, the AC compressor bolt to the negative on the battery? I'm thinking this may remove the whine. Thought I'd ask before possibly damaging the alternator. Or should I move the 3rd wire, the additional ground, to another place on the chassis? Or replace the factory ground with better gauge wire? Thanks for any advice. BIRD

P.S. I thoroughly enjoy the information provided on the website, it has enabled me to maintain and enhance a very nice automobile.