I was wondering if lt4 heads, manifold and the hot cam actually will give you a dyno proven 425+ horse according to summit and almost every performance place. I have a 94 camaro z28 with the lt4 hot cam.. Which heads would give me the best performance and power with the lt4 hot cam. I have the stock lt1 heads. How much rearwheel horspower would I have with the lt4 heads with the lt4 hot cam in my car. How much of A increase hp would the be with the heads - Mike

 

You'll be lucky to see 425 at the flywheel. Don't get suckered in by that. Piece together a kit, or buy the hotcam kit and have your LT1 heads ported. You'll see more power if done that way, and WAY more power if you get something bigger than the hotcam.

 

Do a search, this has been discussed ad nauseum on here. To answer briefly, yes BUT:
First off it's 425HP at the flywheel, not at the wheels (more like it 360RWHP on an M6, or 348RWHP for an A4)
Second, you'll need more than just the kit. You'll also need headers (probably long tubes), CAI, a good ECM tune, and possibly no cats

As to how much you'd gain from just the LT4 heads, a good bit. But again, it also depends on what other mods you have. If you've got headers, CAI, and get your ECM tuned, you should see around 330RWHP on an M6 car with LT4 heads and hotcam.