Can't tell you anything about your times except there are many stock head/stock cammed Stangs out there with not much more done than long tubes, big gears and traction (slicks, rear suspension work) that run 12's.
The P's, GT40 irons and GT40-Y303's (AL) all flow about the same. People make good power with them all the time and they're quite streetable. The Explorer intake shares the same lower with the Cobra and the GT40 - they all flow almost identically. It should work well with the P's. The throttle body is 65mm - but it will take work to adapt it to the Stang - the throttle linkage and the tps will need to be modified to work. It can be done - I'd just buy a 65mm from Ford Racing and get the new tps and IAB solenoid that come with them. The older Explorer intakes have internal egr capability. The newer ones (starting sometime in 97) do not. So if you need to be emissions legal you'll need an earlier intake. None of them have the ACT sensor in the number 5 runner - so you'll either have to drill and tap for that sensor, or lengthen your wiring harness and install it in the intake piping somewhere upstream of the throttle body. The Explorer's had it installed in the air intake box.
Here's a blurb from another post that describes the history of the GT40 intakes:
There are several GT40/Cobra/Explorer style lower intakes. All of these will use the same upper to lower port spacing and bolt pattern and as such; the same gasket.
The 91-93 GT40 as sold by Ford Motorsports had a unique lower intake and possibly a different casting number.
When Ford came out with the 93 Cobra, they retooled the GT40 lower intake molds for the higher volume of mass production.
They are visually and functionally the same. Only difference is in casting techniques used to streamline to the production.
All Motorsport GT40 intakes and 93 Cobra intakes have the holes drilled and tapped for the air charge temperature sensor (ACT) and the throttle body coolant lines. The 93 Cobra had pipe plugs installed in the holes for the throttle body coolant lines since they did not come with the throttle body coolant lines.
Starting with the 1994 Cobras, the holes for the ACT and throttle body lines were no longer drilled, even though the casting bosses where the holes should be were still there. This same lower intake was also used on the 1995 Cobras and the 1996 to very early 1997 Explorers.
Ford again retooled the lower intake for the 1997-2000 Explorers. It is still the same GT40 style intake and the ports are still the same, BUT they do not have an EGR port AND the casting bosses for the ACT and the throttle body lines were eliminated from the casting. If you dont mind losing the EGR function, you could use this lower with no problems other than either trying to drill the ACT hole OR completely relocating the ACT to the inlet tract as Ford had done starting with the 1994 Mustangs.
The Explorer intake is still a very inexpensive upgrade for a stock intake and offers a great bang for the buck. Flow of the upper is probably very similar to a Cobra and not far behind a GT40.
Worst case scenario is to buy and Explorer intake and use it as is until you locate a GT40 upper (if that is what floats your boat).
But the difference in power in minimal.It would have to come down to aestethics.
