We have built and raced both the 440/512 & 400/512...The 400 based fits in the car way better. My first season on the 400/512, and we clicked off a 6.19 last weekend with it. Both run about the same ET in the 6.1's in the 1/8th....If I did it again, I might try the 440/543 kit they have....Cubes is king. All our builds are pump gas.

'70 Cuda,...605 EFI Hemi Street Car (6.20 best pass, 1.33 60ft)
https://www.youtube.com/watch?v=WYw6RA-k5Bk (6.25 at 108.75mph from inside car)
https://www.youtube.com/watch?v=3zQEb9uxFng (6.25 at 108mph from outside car)
https://www.youtube.com/watch?v=JCvfzsC4NgM (9.9)

'66 Barracuda AWB Stretched nose Blown 440 Car in build stage

'71 Duster Drag Car 400 Low Deck 512 best 6.002 at 115.44mph
https://www.youtube.com/watch?v=Znuo3jMUXTk