I'm trying to keep the testing consistent from manifold to manifold in order to get meaningful results, so I won't be using any special spacers on any intake. However, I can tell you that on my 492" FE that I dynoed last spring that the combination of cutting down the plenum divider to a height of 1/2" below the carb pad, plus adding a 1/2" open spacer under the carb, yielded about a 6HP increase over the unmodified plenum divider and no spacer. Hope that helps - Jay
Jay Brown
1968 Shelby GT 500 Convertible, all aluminum 489" 1030 HP Supercharged FE
1969 XL Convertible, 460
1969 R code Mach 1, 706 HP 511" all aluminum FE, 10.457 @ 127.47, 2005 Drag Week Winner, Naturally Aspirated Big Block
