This should be your first stop.
Core2 Overclocking Guidehttp://www.tomshardware.co.uk/forum/259899-11-core-overclocking-guide
Shadow's Gigabyte motherboard OC guide:http://www.tomshardware.co.uk/forum/page-245679_11_0.html
It's for an EP35-DS3L but all the Gigabyte Core2 BIOS's are similar.
Your VID (1.325 volts) is unusually high.
Keep your 4.0 mem multiplier.
You should be able to push the FSB freq up to around 350 MHz. The G41 chipset generally will not run past that.