Hi I have an ef falcon sedan converted manual trying to gain max hp out of a n/a sohc motor I have a stock bottom end with a shaved ported polished 3.9 head with heavy duty valves springs and a reground camtech cam with 4480 headers and 2 and a half inch exhaust what would be the best motor combo to achieve better hp last motor I had built ran 191.3hp with high torque but I'm more after power what parts would help make better power in my new build thanks

I am not sure why you would want to do this to a street-driven car, other than bragging rights. But, here are some suggestions.

If you are starting with the same engine and you are happy to sacrifice bottom-end torque to gain top-end power, the first thing to change is the cam. More duration, and as much lift as you can get. A billet cam will give you the best total flow and better valvetrain geometry for the same duration. Also, a narrower LSA tends to achieve a higher peak power number, but is likely to lose a fair bit of bottom end, and a little at the very top end. Wider LSA tends to flatten the torque curve.

To compensate for the lower effective compression (the valves are closed for a shorter period of time) you can and should increase your mechanical compression ratio by skimming the head or changing the pistons.

Better breathing will always help peak power:
- SS Inductions or similar snorkel
- low-restriction panel filter
- bell-mouthed airbox exit
- mandrel-bent induction tube
- oversize throttle body
- 3-inch exhaust with straight-through muffler and high-flow cat (you won't do much better than the 4480 headers you already have)

And DEFINITELY get a J3 chip and custom tune to match your combo. This will maximise the power out of your mods and you will probably need it anyway to get it to idle decently (or at all) if you go with a big cam.

If you are planning to build a new SOHC engine, you could start with an AU bottom end. This will be much smoother and has a windage tray that helps horsepower, especially at high revs.

If you are looking for maximum N/A horsepower and money is not a consideration, go with the DOHC engine, swap in big cams and do all the same mods as for SOHC. Trav199 on this forum built a street-driven DOHC with 330rwhp/246rwkw - but it wasn't cheap.
the-garage-f53/trav199-bf-n-a-xr6-330rwhp-t99170.html

I understand the motivation to stay N/A. I'm the same. But going for max power at all costs is just going to make the car miserable to drive daily - unless you never go below 3000rpm Others have also gone for max N/A power, which requires a big cam, and have later switched back to a more useable cam.

Anyway, have fun.