Ehh, 25hp may be what you get, you will get more with a test pipe but then you wont pass emissions, a cat back will help more than the cone filter unless the cone filter is rerouted under the head light, but then you run the risk of getting water in it when driving in the rain. You can get a lot more intake noise and a little bit more flow by removing the resonator but in the end the engine was designed to have it, so it may hurt you in the long run.
If you keep the resonator and just replace all the factory accordion hoses with new stuff that would help more than just a cone filter. The big cylinder you have between the throttle body and intake cone is the resonator, that actually helps straiten air waves as they move into the intake.
I don't prefer any of the available headers, they are not really tuned for the engine, certain pipes need to be certain lengths, thats why I'm designing my own.
A good exhaust and intake will make your car more fun to drive and hear, hope this helps, good luck.
Here is one of my concepts:
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Whats in the garage, well.... in the yard.
1986.5 Toyota Supra - NA - 5 spd
1986 Ford Ranger Lowrider - 5 spd
1984 Ford Ranger XLT - 7" Lift - 4X4 - Auto
"Stuck in the 80's"