Racing Fuel Systems

Should I use a Std flow or hi flow?
Holley street hp 950 came with a 4.5 think 6.5 is better.

This is a good question, and I'm curious as well. Looking at my PVCR size versus the windows on the power valve itself, I would think the high-flow valve is unnecessary... there I go thinking again. On the flip side, the high-flow's greater flow area means there's half as much chance of a delivery issue. I'm certainly no expert--that's why I'm here, to learn from them--but my internal logic says "they can't hurt" but sees no real performance gain, at least not at my level (.070" PVCRs). I could be way off base. I'm sure someone more knowledgeable will tell us if I am.

As a general rule of thumb I like to use HF power valves with PVCR's over about .070