.550 lift is stock lift on PI motors. the non-PI were .500
If you are talking about the "Stage 2" Trickflow's, they are intended for use with the new Trick Flow heads.
To my knowledge, they won't work with non-fly cut pistons (valve reliefs), unless you are using the Trick Flow heads, which allow for larger lift and/or duration on a stock PI motor with the Trick Flow heads.
I have personally talked to TrickFlow, the current TF Cams are for PI Heads, they are working on cams for their new TF head.
The cams will work without valve reliefs cut into the piston if installed at 114 intake centerline.
Where did you get that info? It is 100% wrong...
Factory cam lift specs:
NPI-> .461 lift intake .466 lift exhaust
PI-> .504 lift intake .531 lift exhaust
He wasn't flaming, just correcting you. And he's still correct, what he wrote down is accurate , and domestic cams have inch measurements std.woah... hold the flaming but here... u want specs from factory here ya go...
PI ---> (1999-2000 windsor specs)Intake 12.86 mm (0.51 inch) Exhaust 13.56 mm (0.53 inch)
(2001-2004 Romeo specs)intake 13.00 mm (0.51 in) exhaust 13.75 mm (0.54 in)
NON-PI --->(1996-1998)Intake 12.0 mm (0.4724 in) Exhaust 12.0 mm (0.4724 in)
Those are factory specs if you want to be exact there killer...NOTE: Ford specifies all these specs "Theoretical Valve Lift @ Zero Lash"