The dorman is literally an NPI casting advertised and fitted to work with the PI heads. Its garbage and even if it WASN'T leaking you should replace it with an OEM intake. Yes, dear god yes get that PI intake and get it on there. You'll notice a jump in how well the car performs too.
2000 Mustang GT Steeda #0048
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.