I like the sidewinder intakes myself. Still to this day an excellent runner and can be found for around $350 in good shape. On ebay I've seen them go for $500 good used and $800 nos.Swap meets are good for old stuff. Sometimes you hit it right and score a deal. The PI is good and seems to be the standard. If you don't mind the weight a old iron CJ manifold is good to. Same as the PI except CJ's iron and PI aluminum. Some of the vintage Edelbrocks are cool or the newer RPM or Victor. I run an old tripower setup on my "63" 406.myself. G.