I have no dyno numbers. The spring pressure of the 5.7 and 6.4 are very close. Stock 5.7 springs will work. Just slide the cam in. You still are able to utilize the VVT and MDS. I would guess an easy 30 hp.
The LC/LX forums pretty much all say you need the 6.4 valve springs with the swap, even some reports of engine damage without them. Could be operator error (or internet myth), but if the OEM application spec’ed a different spring, it seems prudent to match them.
Seems like the 30 hp is a pretty good guess, and from the limited dyno curves I have seen, no loss on the bottom end like some aftermarket cams have. Unless you are looking for more HP, seems like a win-win to me.
