426 small block

If I could do it all over again, I'd have gone with the Indy 360-1 heads/intake in-lieu of the Trick Flows on my 421.

That's not a knock against Trick Flow. Their heads are awesome. The Indy heads are just more capable IMO. I'm seeing guys run high 9s N/A with them. Larger exhaust ports. They're just "gooder" for my application. Just depends on what you're using the car for.