What horsepower gains can I expect from LT4 heads and intake as I already have the LT4 Hot Cam kit with 1:6 roller rockers and other enhancements listed in my signature.

A safe and enjoyable New Year to everyone!

 

I am going to take a guess that you may see a 35-40rwhp gain over the stock heads/intake combo. This assuming you have a real good tune. There could be a bit more to be gained if you had them ported.

 

35-40 seems a bit on the high side, IMO. My guess is that you'd see ~20, but have a more broad power band.

I would P&P the heads before you put them on. I would use a bigger cam as well, but it's not my car.