diming lights

[Dis00]

whats the brush pack

would a pharad thing work if thats what they are called

[j_s]

Replace/Add thicker cable from Alternator to Battery (4g or even 2g if you can) also Battery earth cable and engine earth cable, you should see an improvement, most people that replace this tend to see significant reduction. If it still does it then a more powerful battery.
I don't bother with powercaps, i'm using one of these instead 
http://www.caraudiodirect.co.uk/product_info.php?products_id=3720&cadid=8a2f7f4dbcb13532b67646365a3ee607
Much much better than any piece of rubbish powercap, no offence everyone but they are a waste of time.

[Bazzer]

whats the brush pack

It's a part on the alternator that transfers the current from the rotating part to the output. They wear out and can be renewed...