Gone are the 2 valve PI heads that were used on the 1999 thru 2004 Mustang GT. I'm guessing that since it has been 10 years since the last 2 valve Mustang rolled off the assembly line that it was time to retire these cylinder heads.
The last time this happened to me was back in 2008. I saw in the Ford Racing catalog that they were still selling the SVO 2 valve heads that went on the 1996 thru 1998 NPI engine. I found a good deal on the SVO intake (seen above) which had been very rare and hard to find. After getting the intake I was saving for the SVO heads. Then in 2009 the SVO heads were gone from the Ford Racing catalog.
Lesson learned. Get your Ford Racing parts while they are still in the catalog. It's a shame, the PI heads came with cams and both could have been had for around $800 - $900 for the pair, new.
So my options now are the new 2 valve Trick Flow Twisted Wedge heads for over $2k for the pair and add another $600 for cams. Get a pair of used / reconditioned PI heads from someone like Modular Head Shop or get a pair of used / reconditioned NPI ported heads for my SVO intake. Those last two would come with cams at around $2.3k for stage 1 or $2.7k for stage 2.
Making power for the 4.6 modular 2 valve engine has just gotten really expensive. Jegs sells a Chevy 350 ci long block (heads and complete lower-end) for under $2k. Add a carburetor and a cam and that would make more power than I could with the any of the combos I listed above.
I'm going to have to think really hard on whether or not to continue with this project....