True. What size power wire are you using? Do you have any additional grounding wires from the battery or just the stock ones?
The capacitor will definitely help, but you should invest in some decent car audio wire (NOT WALMART) and upgrade your power+ground under the hood. The cruddy stock stuff will lead to bottlenecking. In my old hyundai (ftw!) I had a decent system and after I redid all my power+grounds and added more grounds under the hood, the tach no longer dipped and my headlights didn't dim noticibly. All with a stock replacement autozone battery and NO cap.
My car now will bob a bit on the tach with I'm bumping (much more juice drawn) but not that bad since I have a ton of Rockford 4 gauge or 8 gauge for everything everywhere - but I'll be putting in a capacitor this weekend, so long as I am motivated. Maybe I'll do some pics of the install
