[Dwayne J]

You know you should really understand what the parts are before you go looking to swap them. My understanding is your car should have 243 casting heads his car probably 241, YOUR HEADS ARE MUCH BETTER. Hell yours are the most desirable of the cathedral port heads, same casting as used on the LS6. The 243s you should have are so much better guys with Camaros will swap them on unported, usually quoted for about a 15hp gain.

Edit:
The 2002 LS1 seems to have gotten the LS6 intake which is better.

If you wanted to make 15 less HP to keep the tranny alive then the head swap seems like a good idea.

Don't go blindly assuming f-body stuff is better especially when it is so much older. OEMs constantly learn to do things better or find a little more power, or in some cases sure they make something cheaper and hurt power but not nearly as often as they improve.

On the intakes the early LS1 intake is down like 9hp 11tq from a truck intake, but the f-body owners will tell you a truck intake couldn't possibly be good. Now you can not consider a truck intake but the point is "LS1" doesn't make it magical.

GM's 6.0L LS Series Small-Block - Tech - Tune-up - Hot Rod Magazine

 

[Dwayne J]

Properly ported 243s and a cam could add probably 80rwhp IF the rest of the car is setup to handle it. Now a lot of shops could claim to be able to port them, but I would look for someone proven to be good with the LS cathedral heads.

I know the LS6 intake can be done but you will need to look on LS1tech like Mixedimpala04 said, that would be a good place to look into the DOD too.

Really though cars can gain a lot of performance before resorting to things like heads and cam. As Ejbeirs asked what else is done to the car?

 

[Dwayne J]

Also check LS4.com. If you're worried about keeping DOD leave the heads alone. If not look into L87 intake and head swap they're from the LS7. They are usually good for 45-50 whp but you will have to modify the intake manifold. The LS4 Intake manifold is shorter than the rest of the LS series motors. I also agree with check LS1tech.com. I know I own a 13 LTZ but I am a former owner of a 2006 GXP and a 2007 SS I have a little experience with the LS4.

What is an L87 and are you actually suggesting LS7 heads on a 5.3l? I don't think the valves will fit the bore.

 

[Dwayne J]

The 243s are a GREAT head and in terms of actual on track performance many good shops will recommend them ported over even L92s ported even on larger engines much less a little 5.3l.

 

[Dwayne J]

Hell most 6.0l cars are faster with a well worked 243 head than with a rectangle port head. The rectangle port stuff makes a big number but rarely is it actually quickest down track I am fairly certain the valves wont even clear the 5.3l bores, hell shrouding is a problem with the smaller L92 heads and a 6.0l engines bore hence GM coming out with the 6.2l engines. I believe LS7 heads on a 5.3 physically wont fit the valve in the bore much less have room for air to move around the valve.

 

[Dwayne J]

I haven't paid much attention to the intakes as the truck intake is decent, might throw a 07+ intake on it if I could find one cheap as those have a bigger TB and are a little better. NO chance of getting one under a FWD car hood.