When I swapped from my 915 to the normal 440 source stealth heads my car picked up .2 in the 1/4. From what I've found online researching is the basic stealth heads flow around 268 cfm and the CNC version flow around 320ish. I have no idea what my old 915 heads flowed, they were pretty stock with a home port job done. Has anyone swapped from the reg stealth heads to the CNC version? Just curious as to how much I may be able to pick up with the CNC version heads. I'm looking to build a stroker in the future, but don't have all the coins at once to build it, so I thought maybe upgrading my heads now will be one less piece I need down the road.
Rule of thumb is 2 hp per 1 cfm increase. So if the ported heads flow 50 cfm more than the unported heads you would be able to see up to 100 hp gain. I've run this test a few times and the rule of thumb is accurate as long as everything else on the engine can support the power increase.
