Best way to proceed with improving up 427 Windsor street setup

[Ace23]

Originally Posted by SPF1061

I put 2" headers on my Roush 427R. (Dual plane intake with AED 750, 3" Stainless Specialties mufflers). They sounded and felt really good at the very top end for the last 1500 rpm or so, just before it hit the rev limiter@ 6400 rpm. Low end torque was way off. This was verified on the dyno, on the drag strip and daily street driving seat of the pants. Overall performance was better with the stock Superformance headers. I really wanted the bigger headers to be better. In my experience, they weren't. FWIW. Your mileage may vary, so to speak.

Great info on the headers! I thought most Roush 427R's used a single plane intake. Did you change to a dual plane and if so which intake? If you thought the bottom end disappeared with the larger headers and dual plane then you can imagine how mine might feel with 2" and a single plane. My side pipes are currently 2-1/2" but I'm going to 3". We are very close to getting it buttoned back up for a test ride to see if the new fuel system solves the missing power issue.