You should have the skills to make factory-like quality cables of the right thickness and not rly on store bought ones. I spent a lot of money listening to parts counter guy that sold me the wrong size battery cables. Check the groundstrap as well!
A 2 gauge cable cannot get the power to a starter like a double ought cable can. Made that mistake and fixed the problem immediately. Quality solder loaded lugs are available cheep on ebay and star washers are a must.
