what does ls1 with stock 243's put out?
 

Just wondering what swopping 243's onto a stock 02 ls1 will do power wise? it already had the ls6 intake just figured for the price of the heads I would get them from a buddy and put them on. but I am currious on how much I will gain.......

with stock cam...maybe 15hp. marginally better flow, small boost in compression.

while they're off, may as well spend a few extra $$ and get a mild port job and mill them a tad.
that could boost the gain into the 20-30hp range possibly, especially if you get a cam down the road.

i agree about the porting and milling its almost not worth the labor for 15 hp.

when you say 15hp and 20-30hp do you mean rwhp or crank?

rwhp...and its VERY generalized numbers.

can't say i've seen any before/after...apples to apples..comparison between ls1 and untouched ls6 heads.
and only a few comparisons of stock cam with ported heads...although the results were nice.

The LS1 cam is so dead up top that it seems like a crime to pull heads on a motor and leave it in there...