I found some used (200 mi) GT40X heads for $875
 

I would love to buy these, but I am not ready for them yet. If anyone's been looking to get the GT40X heads, here you go.

Price: $ 875.00
Phone: 618-988-9194
E-Mail: YAMAHA@MIDWEST.NET

ForsaleAd: GT40X HEADS. FROM FRPP 392 STROKER CRATE ENGINE. 200 MILES ON HEADS, HEADS ARE UNTOUCHED. 64CC CHAMBERS WITH FRPP 1.6 BOLT-DOWN BLUE ROLLER ROCKERS, COMPLETE. PERFECT FOR 5.0 MUSTANG.

I saw this in an ad on etconnect.com, good luck!