_MG_6549.JPGWanted to share with everybody what the results are. Unfortunately i did NOT flow the manifold as cast on the CNC ported Brodix C head . Everybody seems to agree plenum work is VERY important for performance improvement so i went to work with the die-grinder. After enlarging the carb opening to 3.700" x 3.700" i made the radius's as great as i thought i could without cutting through the roof of the longer runners 1,7,2 and 8 and relieved the others some 3,5,4, and 6. The flow testing up to this point has been on the number 1 cylinder which i figured would be the more restrictive runner? This is an 18 degree head with Brodix's pprogram 254cc runner with a MCSA of 2,53 sq. in. net ( i did subtract for the rounded corners .750" radius). Flow testing was done on a bench which flows very close to a SF 1020 (cant remember the name of the flowbench) but it is a medium blue color. Intake on head with all other manifold runners taped off. .300"=210 .400"=264 .500"=302 .600"=325 .700"=325 I then made a 1" billet spacer and welded it to the intake AND welded on the outside of the plenum and on the top of the runners. Then started the grinding and radius work inside the plenum once again making the radius's a long as possible starting right at the gasket surface and working towards the runner roof downstream. I formed a piece of wire about an 1/8" diameter to conform to the entire radius of #1 runner, it fit to a 5" diam. metal can. which gives some idea of it's size. Results of flow test #2 .300"=208 .400"=267 .500"=315 .600"=343 .700"=350 . The number one intake port (head only) with radius at port mouth flowed as follows .300"=212 .400"=273 .500"=320 .600"=350 .700"=358 . Comments or questions welcome, Mark H.