I wouldn't waste the money on a new intake at this point. You are probably going to spend at least 1500+ between parts and install.
Have you gotten shifter, gears, TB, MAF, pulleys, etc...? If you are looking to do something big, I would do heads before intake mani.
It's a lot more, but heads are a much better HP to $$ ratio than an intake manifold. Getting heads is the best thing you can do to make that GT more comparable (performance-wise) to that Cobra you wish it was
.
96-98s get tough to mod after a certain point. Like Hammer probably realized, there is a point where you pretty much have to go all out. Intakes are way overpriced, but if you want to get a supercharger (or any other FI), you need a new one because otherwise, the plastic one will be blown to bits. Then you can't get a supercharger w/ heads because the compression will be too high.
My friend has a 98 GT 5sp and he is looking to sell for a 94-95 Cobra (with low miles). He got frustrated with the idea of having to spend $8200 (suprcharger, heads, intake) where I could spend less than $3500 and get the same parts with the same or better performance gains. Not to mention that he couldn't run that combo without more engine modifications.
Sooooo, if you love your car, keep it... just don't spend all that $$ for an intake (My upper and lower cobra intake cost me a total that was in the high 300s.) Get all the little things, then maybe if you are going heads or supercharger you can get it.
Just my $.02
Thanks,
DoranW