1NZ port & polish

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Originally Posted by ChinoCharles

10.75:1 at worst, 11.5:1 66% of the powerband.

9.5 was a hypothetical.

2000-5000 RPM: about 11.5:1 AFR
5000-5800 RPM: descends to 10.75:1
5800 on: stays around 10.75:1, horsepower flattens out, torque decreases 10%.

Taking AFR through through the tailpipe on a dyno through OEM cats will give you invlalid results. You need a wideband with a bung installed pre cat.

Your mileage will improve after a tune. That is if you aren't flooring it more than you were to begin with.

If you are gonna get a PnP done free by a reputable shop in your area, yes It may be worth it. If some toolbox shop does it, it will most likely do more harm than good. I wouldn't pay to have it done to this motor. The funds are better spent elsewhere, either an engine swap, or a turbo\supercharger.

I used to work at a shop porting cylinder heads for many championship race teams in various forms of racing, so I know all the processes and methodologies pretty well. Moose is correct, although I doubt you would see 15 Hp on this particular engine without cams or other component upgrades.