I am running a walbro 255 which I recently put on, you can get them for around $100.00. Just one and it is keeping up with my car on e85 at 85psi. I run around 10-11 psi of boost. I the biggest restriction I found on the factory fuel pumps is the fitting with the check valve on the pump. Where the banjo fitting is. There is one small 3-4mm hole that all the fuel has to go through. I never noticed this before and was running into fuel pressure problems like a brick wall at 6000 rpm. It was like the pumps turned off.