[My427stang]

I have run all those manifolds, RPM, F427, Alum PI, and sidewinder. They are within 1-2 horse of each other and any of them IMO would be undetectable from the other if you didnt know it was swapped.

If it were me I'd use this priority

1. Performer RPM (because its new and easy to find)
2. Edelbrock F427 (old, but pretty darn close to the RPM, no cheaper usually)
3. 428 PI Great intake but worth bucks to collectors, better to use new tech for same or cheaper with RPM, plus exh crossovers frequently rot out
4. Sidewinder - Another great intake but offset carb makes for a PIA most of the time, plus weirdness brings big dollars LOL


With those above, like I said, I'd bet a dollar you couldnt tell a difference with any other changes. Save the PI and sidewinders for the guys who want them, buy a new RPM and off you go, or buy a used F427 in nice shape and run right along side the RPM's