Originally Posted by StealthFormula
If you do some searching around you'll find a ton of threads on the power difference some with before/after dyno graphs so it will give you a nice idea of what to expect.
I say go for it. If you're already in there to swap in a cam and the associated valve train components then it's really not much more work to swap the heads. If you do decide to install 243s, I'd suggest getting some .40" cometic head gaskets to improve your quench and boost the compression further.
I apologize I got mixed up, I did some searching and the threads with before/after dyno results that I was referring to is for the ls6 cam not the ls6 heads. FWIW, I wouldn't be surprised if the heads would be worth ~20hp on a cam-only car.