Is there any difference between '04 LS1 GTO heads and the heads on my '99 Z28?

 

nope - both should be #241 LS1 heads.

The 04 GTO's have the advantage of an LS6 intake compared to your LS1.

 

[QUOTE=MachinistOne;6217836]nope - both should be #241 LS1 heads.

[QUOTE]

Wrong, the 241s came out in 2001 and some late 00s. 99s were the 853s but there are not enough differences in them to make a swap worth the time and money

 

The reason I was asking is because I had heard they had the 243 heads. I thought that was the reason they were rated at 350 hp and not 325 like an '01-'02 SS for example.

 

Same basic heads (different casting number), same power, same motor.

All LS1s make around 350 crank horsepower stock -- Vettes, F-bodies, and Goats.

The LS6 heads are found on LS2s (243 casting).

 

Ahh...so I see says the blind man. The '05-'06 GTO's have the 243s.

 

[QUOTE=AL SS590 M6;6217926][QUOTE=MachinistOne;6217836]nope - both should be #241 LS1 heads.



Forgot about the 853's - just know they're not the early 806 or late 243

 

What's the deal with the 806s and the late 243s? Where do my 853s stack up against them?

 

flow and power potential is the same, the only difference is the early 806 uses perimeter bolt hole valve covers.

 

243s are LS6 heads which are a much better head than any LS1 head.

 

Yeah I want to get some 243 heads I have seen some really good deals on them coming from vettes but no cash man I am kicking myself.