Kind of depends with the main and fogs. I tried hids in the main beams (9005) on mine, and the warm up time when first switched on (gets better if main be stays on for a while and only switch off for short periods) meant you got no benefit initially, so proved to be cr&p for me. So it really depends on the how busy the back roads around you are. Only reason I can think to swap fogs is for the colour match, but unless you cruise with them on, who will see? Yellow (yellower) is better for fog penetration anyway, so they are counter productive from a performance perspective. For led sidelights, the cheap LEDs are too blue (even the white ones) so don't match the headlamp temp at all, but the more expensive Philips 6000k 501 LEDs are excellent, but are about £20 for a pair (well worth it IMO).