Enhancers? If you mean potentiators, some people find that MAOI's, such as harmalas or passionflower, can increase the effects of LSD. I found that celastrus paniculatus seeds (an MAOI) increased the potency of an LSD experience I had by a significant amount. I've also heard clove oil can help with absorption but I've never tried it.
If your dosage is accurate, I assure you that you won't need a stronger trip. 500ug is a lot of LSD, someone should warn you that you may not know what you're in for. Your average blotter has 75-115 mics on it, with most of it leaning towards the lower half of that statistic. 200ug blotters are very uncommon but not unheard of. So, 500 micrograms would be enough for 5 ordinary people to all have a decent trip.
8 days is enough for your tolerance to be somewhere around 15% higher than if you had no tolerance at all, generally speaking.