Gutter underground downspout help
Recently moved into a house and discovered during hard rain storms the downspout that cover around 1,500sq ft of roof at the front of my house overflows violently during very heavy rain. I had underground 4” corrugated pipe. After not finding any blockages in the corrugated I had a landscape company quote $5,200 to dig up about 60 feet of corrugated pipe and replace with 4” pvc as a proposed solution. After I got over the shock of the quote I decided to tackle the job myself for about $500 in parts.
Well after spending all weekend digging and replacing the entire run with 4”PVC, it’s much better, but still overflows. I’m looking for suggestions on how to improve this? Do I connect into the main line at a 45 degree to help with flow? Do I split the main flow and y into the abandoned corrugated pipe to handle extra volume? Is it time to move? Or do I need to call the landscape company? Thanks for any help / insights.