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Message: <blockquote data-quote="96blak54" data-source="post: 1404340" data-attributes="member: 14727">1st questionWe all are glad you are here! Dont be shy to represent your bird over in the build thread. 2ndMy findings of 5.4l npi head is revised with bigger water cavities, opened exhaust bowl and port, and thicker deck surface. Intake port is the same, valve seat cut is the same, bowl contours the same. Chamber shape the same. Nearly all the same except exhaust port, water cavities, thicker deck. A 4.6l npi crutch is the pinched exhaust port and can wake up a npi engine just by carving it open. The 5.4l head already has the opening needed, plus the port has a ton of material if more area is desired. Why baffles me, but options to the builder.Nearly 98% of all heads ever made were designed with the valve angle towards the inside of the engine,  making the intake valve tulip an obstruction / obstacle for the incoming blast of air.....needing all 360Â° of the valve opening. Not to mention flowing caracteristics over the valve at different valve lifts. Modular heads valve angle is towards the outside making the valve tulip non-obstructive to the port angle allowing the blast to skim directly over the valve backside regardless of any lift....not needing 360Â° of valve area. Heck, the valve is shrouded 75%!!  Chamber shape along with plug placement flowing along with cyclonic action(better known as swirl) Couple all this with a tiny bore means a nasty swirl that is uniformly stratified (meaning the same action through out the bore during incoming stroke). Detonation resistance.  Preignition is truly eliminated.This is why the mod 2v is so mighty!With all this said, porting a set of npi heads is almost fool proof. Pi heads,...different story. A little more tricky.</blockquote>