The O/S valves should be your next mechanical upgrade.
Port matching the intake and head with the intake gasket is cheap, and will help a little w/air flow.
If the "cold air" intake is sucking engine bay air, it will not help with performance, as its ability to draw more air into the engine isnegated by it being heated air. If you have some fab skills, you can isolate the intake and plumb an outside air source to feed the intake, wrapping the intake tubing an intake isolation chamber with DEI "cool tape", will keep the air at outside temp until it reaches the intake manifold. This is what I designed about 18yrs ago for my 3.0
On a 95* day at idle the engine bay side was 135*, the intake chamber was 98*.
Nothing but cool air and bugs with a snorkel.
