If 600w is making your lights dim, go to autozone and have your alternator tested. If comes out substantially lower than the factory rating, by all means get a new alternator. Don't bother getting a HO alternator unless you can get it for the same price. 130A from the stock alternator is overkill for 98% of the audio installs on this site. Don't bother with a cap if the alternator is failing, the last thing you need is another load on it.
