Re: non HO to HO swap?
There are 17 differences between the 4.7 and 4.7 HO:
1. Block - Detonation sensor bosses in the valley
2. Camshaft - custom profile lobes (designed for increased performance)
3. Connecting rods - modified, with floating wrist pins (vs pressed-fit pins in standard V8)
4. Crankshaft - forged steel (vs cast iron in standard V8)
5. Crankshaft damper - unique to H.O.
6. Cylinder heads - different shaped combustion chambers (for improved airflow). The letters "H.O." are cast on the front end of the heads.
7. Exhaust tip - chrome (2002 models only, decontented for 2003 models. Available only as a one-piece assembly with muffler)
8. Fuel injectors - higher flow (+3.3 lb/hr)
9. Intake manifold - modified (shorter runners)
10. Intake - low-restriction intake system (different resonator, air filter, air filter hose and housing)
11. Knock sensors - two, stereo
12. Main bearings - tri-metal (vs bi-metal in standard V8, designed specifically for the HO engine)
13. PCM calibration - unique programming
14. Pistons - dome shaped for increased compression ratio
15. Spark plugs - platinum tipped
16. Valves - unique exhaust valves (same lift as standard V8)
17. Valve springs - upgraded valve springs (intake & exhaust. Larger diameter wire and more coils)