I just purchased two EVL-18D4, three 2000.1 amps and the OFC 0 Gauge. I with purchase one more amp and six more 18's. Skar Audio products are awesome and I wish they would send decals and banners when I show the vehicle off. Everything will be Skar Audio accept the head unit.
Have had a pair of 18s in my back seat for a little over a year and they crush. Running on a RP3500 and solid electrical and I can hammer them with no problem. Don't get me wrong, I'm not "loud" but they make people jump out so loud enough.
I've had these subs for years now with no issues. Paired with an RP.3500. Insane for the price and the most reliable equipment I have ever used.