aimloan.com says 4.875% for jumbo conforming. Your middle score has to be higher than the threshold (it was 740 6 months ago) to get that and you need to put 20% down. If you put 25%+ down you get the advertised rate regardless of the credit score (again, 6 months old info).

They have $300-500 discount in their newsletter, I can try to dig through my old emails tomorrow morning. I don’t think there is a specific coupon code, you just need to ask for it when you apply for the loan.